15 Feb, 2017
1 commit
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commit a810007afe239d59c1115fcaa06eb5b480f876e9 upstream.
Commit 210e7a43fa90 ("mm: SLUB freelist randomization") broke USB hub
initialisation as described inhttps://bugzilla.kernel.org/show_bug.cgi?id=177551.
Bail out early from init_cache_random_seq if s->random_seq is already
initialised. This prevents destroying the previously computed
random_seq offsets later in the function.If the offsets are destroyed, then shuffle_freelist will truncate
page->freelist to just the first object (orphaning the rest).Fixes: 210e7a43fa90 ("mm: SLUB freelist randomization")
Link: http://lkml.kernel.org/r/20170207140707.20824-1-sean@erifax.org
Signed-off-by: Sean Rees
Reported-by:
Cc: Christoph Lameter
Cc: Pekka Enberg
Cc: David Rientjes
Cc: Joonsoo Kim
Cc: Thomas Garnier
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
Signed-off-by: Greg Kroah-Hartman
09 Feb, 2017
4 commits
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commit 5abf186a30a89d5b9c18a6bf93a2c192c9fd52f6 upstream.
do_generic_file_read() can be told to perform a large request from
userspace. If the system is under OOM and the reading task is the OOM
victim then it has an access to memory reserves and finishing the full
request can lead to the full memory depletion which is dangerous. Make
sure we rather go with a short read and allow the killed task to
terminate.Link: http://lkml.kernel.org/r/20170201092706.9966-3-mhocko@kernel.org
Signed-off-by: Michal Hocko
Reviewed-by: Christoph Hellwig
Cc: Tetsuo Handa
Cc: Al Viro
Cc:
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
Signed-off-by: Greg Kroah-Hartman -
commit a96dfddbcc04336bbed50dc2b24823e45e09e80c upstream.
Reading a sysfs "memoryN/valid_zones" file leads to the following oops
when the first page of a range is not backed by struct page.
show_valid_zones() assumes that 'start_pfn' is always valid for
page_zone().BUG: unable to handle kernel paging request at ffffea017a000000
IP: show_valid_zones+0x6f/0x160This issue may happen on x86-64 systems with 64GiB or more memory since
their memory block size is bumped up to 2GiB. [1] An example of such
systems is desribed below. 0x3240000000 is only aligned by 1GiB and
this memory block starts from 0x3200000000, which is not backed by
struct page.BIOS-e820: [mem 0x0000003240000000-0x000000603fffffff] usable
Since test_pages_in_a_zone() already checks holes, fix this issue by
extending this function to return 'valid_start' and 'valid_end' for a
given range. show_valid_zones() then proceeds with the valid range.[1] 'Commit bdee237c0343 ("x86: mm: Use 2GB memory block size on
large-memory x86-64 systems")'Link: http://lkml.kernel.org/r/20170127222149.30893-3-toshi.kani@hpe.com
Signed-off-by: Toshi Kani
Cc: Greg Kroah-Hartman
Cc: Zhang Zhen
Cc: Reza Arbab
Cc: David Rientjes
Cc: Dan Williams
Signed-off-by: Greg Kroah-HartmanSigned-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
commit deb88a2a19e85842d79ba96b05031739ec327ff4 upstream.
Patch series "fix a kernel oops when reading sysfs valid_zones", v2.
A sysfs memory file is created for each 2GiB memory block on x86-64 when
the system has 64GiB or more memory. [1] When the start address of a
memory block is not backed by struct page, i.e. a memory range is not
aligned by 2GiB, reading its 'valid_zones' attribute file leads to a
kernel oops. This issue was observed on multiple x86-64 systems with
more than 64GiB of memory. This patch-set fixes this issue.Patch 1 first fixes an issue in test_pages_in_a_zone(), which does not
test the start section.Patch 2 then fixes the kernel oops by extending test_pages_in_a_zone()
to return valid [start, end).Note for stable kernels: The memory block size change was made by commit
bdee237c0343 ("x86: mm: Use 2GB memory block size on large-memory x86-64
systems"), which was accepted to 3.9. However, this patch-set depends
on (and fixes) the change to test_pages_in_a_zone() made by commit
5f0f2887f4de ("mm/memory_hotplug.c: check for missing sections in
test_pages_in_a_zone()"), which was accepted to 4.4.So, I recommend that we backport it up to 4.4.
[1] 'Commit bdee237c0343 ("x86: mm: Use 2GB memory block size on
large-memory x86-64 systems")'This patch (of 2):
test_pages_in_a_zone() does not check 'start_pfn' when it is aligned by
section since 'sec_end_pfn' is set equal to 'pfn'. Since this function
is called for testing the range of a sysfs memory file, 'start_pfn' is
always aligned by section.Fix it by properly setting 'sec_end_pfn' to the next section pfn.
Also make sure that this function returns 1 only when the range belongs
to a zone.Link: http://lkml.kernel.org/r/20170127222149.30893-2-toshi.kani@hpe.com
Signed-off-by: Toshi Kani
Cc: Andrew Banman
Cc: Reza Arbab
Cc: Greg KH
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
Signed-off-by: Greg Kroah-Hartman -
commit d7b028f56a971a2e4d8d7887540a144eeefcd4ab upstream.
Add zswap_init_failed bool that prevents changing any of the module
params, if init_zswap() fails, and set zswap_enabled to false. Change
'enabled' param to a callback, and check zswap_init_failed before
allowing any change to 'enabled', 'zpool', or 'compressor' params.Any driver that is built-in to the kernel will not be unloaded if its
init function returns error, and its module params remain accessible for
users to change via sysfs. Since zswap uses param callbacks, which
assume that zswap has been initialized, changing the zswap params after
a failed initialization will result in WARNING due to the param
callbacks expecting a pool to already exist. This prevents that by
immediately exiting any of the param callbacks if initialization failed.This was reported here:
https://marc.info/?l=linux-mm&m=147004228125528&w=4And fixes this WARNING:
[ 429.723476] WARNING: CPU: 0 PID: 5140 at mm/zswap.c:503 __zswap_pool_current+0x56/0x60The warning is just noise, and not serious. However, when init fails,
zswap frees all its percpu dstmem pages and its kmem cache. The kmem
cache might be serious, if kmem_cache_alloc(NULL, gfp) has problems; but
the percpu dstmem pages are definitely a problem, as they're used as
temporary buffer for compressed pages before copying into place in the
zpool.If the user does get zswap enabled after an init failure, then zswap
will likely Oops on the first page it tries to compress (or worse, start
corrupting memory).Fixes: 90b0fc26d5db ("zswap: change zpool/compressor at runtime")
Link: http://lkml.kernel.org/r/20170124200259.16191-2-ddstreet@ieee.org
Signed-off-by: Dan Streetman
Reported-by: Marcin Miroslaw
Cc: Seth Jennings
Cc: Michal Hocko
Cc: Sergey Senozhatsky
Cc: Minchan Kim
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
Signed-off-by: Greg Kroah-Hartman
01 Feb, 2017
8 commits
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commit 3674534b775354516e5c148ea48f51d4d1909a78 upstream.
When memory.move_charge_at_immigrate is enabled and precharges are
depleted during move, mem_cgroup_move_charge_pte_range() will attempt to
increase the size of the precharge.Prevent precharges from ever looping by setting __GFP_NORETRY. This was
probably the intention of the GFP_KERNEL & ~__GFP_NORETRY, which is
pointless as written.Fixes: 0029e19ebf84 ("mm: memcontrol: remove explicit OOM parameter in charge path")
Link: http://lkml.kernel.org/r/alpine.DEB.2.10.1701130208510.69402@chino.kir.corp.google.com
Signed-off-by: David Rientjes
Acked-by: Michal Hocko
Cc: Johannes Weiner
Cc: Vladimir Davydov
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
Signed-off-by: Greg Kroah-Hartman -
commit 8a1f780e7f28c7c1d640118242cf68d528c456cd upstream.
online_{kernel|movable} is used to change the memory zone to
ZONE_{NORMAL|MOVABLE} and online the memory.To check that memory zone can be changed, zone_can_shift() is used.
Currently the function returns minus integer value, plus integer
value and 0. When the function returns minus or plus integer value,
it means that the memory zone can be changed to ZONE_{NORNAL|MOVABLE}.But when the function returns 0, there are two meanings.
One of the meanings is that the memory zone does not need to be changed.
For example, when memory is in ZONE_NORMAL and onlined by online_kernel
the memory zone does not need to be changed.Another meaning is that the memory zone cannot be changed. When memory
is in ZONE_NORMAL and onlined by online_movable, the memory zone may
not be changed to ZONE_MOVALBE due to memory online limitation(see
Documentation/memory-hotplug.txt). In this case, memory must not be
onlined.The patch changes the return type of zone_can_shift() so that memory
online operation fails when memory zone cannot be changed as follows:Before applying patch:
# grep -A 35 "Node 2" /proc/zoneinfo
Node 2, zone Normal
node_scanned 0
spanned 8388608
present 7864320
managed 7864320
# echo online_movable > memory4097/state
# grep -A 35 "Node 2" /proc/zoneinfo
Node 2, zone Normal
node_scanned 0
spanned 8388608
present 8388608
managed 8388608online_movable operation succeeded. But memory is onlined as
ZONE_NORMAL, not ZONE_MOVABLE.After applying patch:
# grep -A 35 "Node 2" /proc/zoneinfo
Node 2, zone Normal
node_scanned 0
spanned 8388608
present 7864320
managed 7864320
# echo online_movable > memory4097/state
bash: echo: write error: Invalid argument
# grep -A 35 "Node 2" /proc/zoneinfo
Node 2, zone Normal
node_scanned 0
spanned 8388608
present 7864320
managed 7864320online_movable operation failed because of failure of changing
the memory zone from ZONE_NORMAL to ZONE_MOVABLEFixes: df429ac03936 ("memory-hotplug: more general validation of zone during online")
Link: http://lkml.kernel.org/r/2f9c3837-33d7-b6e5-59c0-6ca4372b2d84@gmail.com
Signed-off-by: Yasuaki Ishimatsu
Reviewed-by: Reza Arbab
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
Signed-off-by: Greg Kroah-Hartman -
commit e47483bca2cc59a4593b37a270b16ee42b1d9f08 upstream.
Ganapatrao Kulkarni reported that the LTP test cpuset01 in stress mode
triggers OOM killer in few seconds, despite lots of free memory. The
test attempts to repeatedly fault in memory in one process in a cpuset,
while changing allowed nodes of the cpuset between 0 and 1 in another
process.The problem comes from insufficient protection against cpuset changes,
which can cause get_page_from_freelist() to consider all zones as
non-eligible due to nodemask and/or current->mems_allowed. This was
masked in the past by sufficient retries, but since commit 682a3385e773
("mm, page_alloc: inline the fast path of the zonelist iterator") we fix
the preferred_zoneref once, and don't iterate over the whole zonelist in
further attempts, thus the only eligible zones might be placed in the
zonelist before our starting point and we always miss them.A previous patch fixed this problem for current->mems_allowed. However,
cpuset changes also update the task's mempolicy nodemask. The fix has
two parts. We have to repeat the preferred_zoneref search when we
detect cpuset update by way of seqcount, and we have to check the
seqcount before considering OOM.[akpm@linux-foundation.org: fix typo in comment]
Link: http://lkml.kernel.org/r/20170120103843.24587-5-vbabka@suse.cz
Fixes: c33d6c06f60f ("mm, page_alloc: avoid looking up the first zone in a zonelist twice")
Signed-off-by: Vlastimil Babka
Reported-by: Ganapatrao Kulkarni
Acked-by: Mel Gorman
Acked-by: Hillf Danton
Cc: Michal Hocko
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
Signed-off-by: Greg Kroah-Hartman -
commit 5ce9bfef1d27944c119a397a9d827bef795487ce upstream.
This is a preparation for the following patch to make review simpler.
While the primary motivation is a bug fix, this also simplifies the fast
path, although the moved code is only enabled when cpusets are in use.Link: http://lkml.kernel.org/r/20170120103843.24587-4-vbabka@suse.cz
Signed-off-by: Vlastimil Babka
Acked-by: Mel Gorman
Acked-by: Hillf Danton
Cc: Ganapatrao Kulkarni
Cc: Michal Hocko
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
Signed-off-by: Greg Kroah-Hartman -
commit 16096c25bf0ca5d87e4fa6ec6108ba53feead212 upstream.
Ganapatrao Kulkarni reported that the LTP test cpuset01 in stress mode
triggers OOM killer in few seconds, despite lots of free memory. The
test attempts to repeatedly fault in memory in one process in a cpuset,
while changing allowed nodes of the cpuset between 0 and 1 in another
process.One possible cause is that in the fast path we find the preferred
zoneref according to current mems_allowed, so that it points to the
middle of the zonelist, skipping e.g. zones of node 1 completely. If
the mems_allowed is updated to contain only node 1, we never reach it in
the zonelist, and trigger OOM before checking the cpuset_mems_cookie.This patch fixes the particular case by redoing the preferred zoneref
search if we switch back to the original nodemask. The condition is
also slightly changed so that when the last non-root cpuset is removed,
we don't miss it.Note that this is not a full fix, and more patches will follow.
Link: http://lkml.kernel.org/r/20170120103843.24587-3-vbabka@suse.cz
Fixes: 682a3385e773 ("mm, page_alloc: inline the fast path of the zonelist iterator")
Signed-off-by: Vlastimil Babka
Reported-by: Ganapatrao Kulkarni
Acked-by: Michal Hocko
Acked-by: Mel Gorman
Acked-by: Hillf Danton
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
Signed-off-by: Greg Kroah-Hartman -
commit ea57485af8f4221312a5a95d63c382b45e7840dc upstream.
Patch series "fix premature OOM regression in 4.7+ due to cpuset races".
This is v2 of my attempt to fix the recent report based on LTP cpuset
stress test [1]. The intention is to go to stable 4.9 LTSS with this,
as triggering repeated OOMs is not nice. That's why the patches try to
be not too intrusive.Unfortunately why investigating I found that modifying the testcase to
use per-VMA policies instead of per-task policies will bring the OOM's
back, but that seems to be much older and harder to fix problem. I have
posted a RFC [2] but I believe that fixing the recent regressions has a
higher priority.Longer-term we might try to think how to fix the cpuset mess in a better
and less error prone way. I was for example very surprised to learn,
that cpuset updates change not only task->mems_allowed, but also
nodemask of mempolicies. Until now I expected the parameter to
alloc_pages_nodemask() to be stable. I wonder why do we then treat
cpusets specially in get_page_from_freelist() and distinguish HARDWALL
etc, when there's unconditional intersection between mempolicy and
cpuset. I would expect the nodemask adjustment for saving overhead in
g_p_f(), but that clearly doesn't happen in the current form. So we
have both crazy complexity and overhead, AFAICS.[1] https://lkml.kernel.org/r/CAFpQJXUq-JuEP=QPidy4p_=FN0rkH5Z-kfB4qBvsf6jMS87Edg@mail.gmail.com
[2] https://lkml.kernel.org/r/7c459f26-13a6-a817-e508-b65b903a8378@suse.czThis patch (of 4):
Since commit c33d6c06f60f ("mm, page_alloc: avoid looking up the first
zone in a zonelist twice") we have a wrong check for NULL preferred_zone,
which can theoretically happen due to concurrent cpuset modification. We
check the zoneref pointer which is never NULL and we should check the zone
pointer. Also document this in first_zones_zonelist() comment per Michal
Hocko.Fixes: c33d6c06f60f ("mm, page_alloc: avoid looking up the first zone in a zonelist twice")
Link: http://lkml.kernel.org/r/20170120103843.24587-2-vbabka@suse.cz
Signed-off-by: Vlastimil Babka
Acked-by: Mel Gorman
Acked-by: Hillf Danton
Cc: Ganapatrao Kulkarni
Cc: Michal Hocko
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
Signed-off-by: Greg Kroah-Hartman -
commit d51e9894d27492783fc6d1b489070b4ba66ce969 upstream.
Since commit be97a41b291e ("mm/mempolicy.c: merge alloc_hugepage_vma to
alloc_pages_vma") alloc_pages_vma() can potentially free a mempolicy by
mpol_cond_put() before accessing the embedded nodemask by
__alloc_pages_nodemask(). The commit log says it's so "we can use a
single exit path within the function" but that's clearly wrong. We can
still do that when doing mpol_cond_put() after the allocation attempt.Make sure the mempolicy is not freed prematurely, otherwise
__alloc_pages_nodemask() can end up using a bogus nodemask, which could
lead e.g. to premature OOM.Fixes: be97a41b291e ("mm/mempolicy.c: merge alloc_hugepage_vma to alloc_pages_vma")
Link: http://lkml.kernel.org/r/20170118141124.8345-1-vbabka@suse.cz
Signed-off-by: Vlastimil Babka
Acked-by: Kirill A. Shutemov
Acked-by: Michal Hocko
Acked-by: David Rientjes
Cc: Aneesh Kumar K.V
Cc: Andrea Arcangeli
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
Signed-off-by: Greg Kroah-Hartman -
commit 8310d48b125d19fcd9521d83b8293e63eb1646aa upstream.
In commit 19be0eaffa3a ("mm: remove gup_flags FOLL_WRITE games from
__get_user_pages()"), the mm code was changed from unsetting FOLL_WRITE
after a COW was resolved to setting the (newly introduced) FOLL_COW
instead. Simultaneously, the check in gup.c was updated to still allow
writes with FOLL_FORCE set if FOLL_COW had also been set.However, a similar check in huge_memory.c was forgotten. As a result,
remote memory writes to ro regions of memory backed by transparent huge
pages cause an infinite loop in the kernel (handle_mm_fault sets
FOLL_COW and returns 0 causing a retry, but follow_trans_huge_pmd bails
out immidiately because `(flags & FOLL_WRITE) && !pmd_write(*pmd)` is
true.While in this state the process is stil SIGKILLable, but little else
works (e.g. no ptrace attach, no other signals). This is easily
reproduced with the following code (assuming thp are set to always):#include
#include
#include
#include
#include
#include
#include
#include
#include
#include#define TEST_SIZE 5 * 1024 * 1024
int main(void) {
int status;
pid_t child;
int fd = open("/proc/self/mem", O_RDWR);
void *addr = mmap(NULL, TEST_SIZE, PROT_READ,
MAP_ANONYMOUS | MAP_PRIVATE, 0, 0);
assert(addr != MAP_FAILED);
pid_t parent_pid = getpid();
if ((child = fork()) == 0) {
void *addr2 = mmap(NULL, TEST_SIZE, PROT_READ | PROT_WRITE,
MAP_ANONYMOUS | MAP_PRIVATE, 0, 0);
assert(addr2 != MAP_FAILED);
memset(addr2, 'a', TEST_SIZE);
pwrite(fd, addr2, TEST_SIZE, (uintptr_t)addr);
return 0;
}
assert(child == waitpid(child, &status, 0));
assert(WIFEXITED(status) && WEXITSTATUS(status) == 0);
return 0;
}Fix this by updating follow_trans_huge_pmd in huge_memory.c analogously
to the update in gup.c in the original commit. The same pattern exists
in follow_devmap_pmd. However, we should not be able to reach that
check with FOLL_COW set, so add WARN_ONCE to make sure we notice if we
ever do.[akpm@linux-foundation.org: coding-style fixes]
Link: http://lkml.kernel.org/r/20170106015025.GA38411@juliacomputing.com
Signed-off-by: Keno Fischer
Acked-by: Kirill A. Shutemov
Cc: Greg Thelen
Cc: Nicholas Piggin
Cc: Willy Tarreau
Cc: Oleg Nesterov
Cc: Kees Cook
Cc: Andy Lutomirski
Cc: Michal Hocko
Cc: Hugh Dickins
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
Signed-off-by: Greg Kroah-Hartman
20 Jan, 2017
6 commits
-
commit e5bbc8a6c992901058bc09e2ce01d16c111ff047 upstream.
return_unused_surplus_pages() decrements the global reservation count,
and frees any unused surplus pages that were backing the reservation.Commit 7848a4bf51b3 ("mm/hugetlb.c: add cond_resched_lock() in
return_unused_surplus_pages()") added a call to cond_resched_lock in the
loop freeing the pages.As a result, the hugetlb_lock could be dropped, and someone else could
use the pages that will be freed in subsequent iterations of the loop.
This could result in inconsistent global hugetlb page state, application
api failures (such as mmap) failures or application crashes.When dropping the lock in return_unused_surplus_pages, make sure that
the global reservation count (resv_huge_pages) remains sufficiently
large to prevent someone else from claiming pages about to be freed.Analyzed by Paul Cassella.
Fixes: 7848a4bf51b3 ("mm/hugetlb.c: add cond_resched_lock() in return_unused_surplus_pages()")
Link: http://lkml.kernel.org/r/1483991767-6879-1-git-send-email-mike.kravetz@oracle.com
Signed-off-by: Mike Kravetz
Reported-by: Paul Cassella
Suggested-by: Michal Hocko
Cc: Masayoshi Mizuma
Cc: Naoya Horiguchi
Cc: Aneesh Kumar
Cc: Hillf Danton
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
Signed-off-by: Greg Kroah-Hartman -
commit c4e490cf148e85ead0d1b1c2caaba833f1d5b29f upstream.
This patch fixes a bug in the freelist randomization code. When a high
random number is used, the freelist will contain duplicate entries. It
will result in different allocations sharing the same chunk.It will result in odd behaviours and crashes. It should be uncommon but
it depends on the machines. We saw it happening more often on some
machines (every few hours of running tests).Fixes: c7ce4f60ac19 ("mm: SLAB freelist randomization")
Link: http://lkml.kernel.org/r/20170103181908.143178-1-thgarnie@google.com
Signed-off-by: John Sperbeck
Signed-off-by: Thomas Garnier
Cc: Christoph Lameter
Cc: Pekka Enberg
Cc: David Rientjes
Cc: Joonsoo Kim
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
Signed-off-by: Greg Kroah-Hartman -
commit f05714293a591038304ddae7cb0dd747bb3786cc upstream.
During developemnt for zram-swap asynchronous writeback, I found strange
corruption of compressed page, resulting in:Modules linked in: zram(E)
CPU: 3 PID: 1520 Comm: zramd-1 Tainted: G E 4.8.0-mm1-00320-ge0d4894c9c38-dirty #3274
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Ubuntu-1.8.2-1ubuntu1 04/01/2014
task: ffff88007620b840 task.stack: ffff880078090000
RIP: set_freeobj.part.43+0x1c/0x1f
RSP: 0018:ffff880078093ca8 EFLAGS: 00010246
RAX: 0000000000000018 RBX: ffff880076798d88 RCX: ffffffff81c408c8
RDX: 0000000000000018 RSI: 0000000000000000 RDI: 0000000000000246
RBP: ffff880078093cb0 R08: 0000000000000000 R09: 0000000000000000
R10: ffff88005bc43030 R11: 0000000000001df3 R12: ffff880076798d88
R13: 000000000005bc43 R14: ffff88007819d1b8 R15: 0000000000000001
FS: 0000000000000000(0000) GS:ffff88007e380000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fc934048f20 CR3: 0000000077b01000 CR4: 00000000000406e0
Call Trace:
obj_malloc+0x22b/0x260
zs_malloc+0x1e4/0x580
zram_bvec_rw+0x4cd/0x830 [zram]
page_requests_rw+0x9c/0x130 [zram]
zram_thread+0xe6/0x173 [zram]
kthread+0xca/0xe0
ret_from_fork+0x25/0x30With investigation, it reveals currently stable page doesn't support
anonymous page. IOW, reuse_swap_page can reuse the page without waiting
writeback completion so it can overwrite page zram is compressing.Unfortunately, zram has used per-cpu stream feature from v4.7.
It aims for increasing cache hit ratio of scratch buffer for
compressing. Downside of that approach is that zram should ask
memory space for compressed page in per-cpu context which requires
stricted gfp flag which could be failed. If so, it retries to
allocate memory space out of per-cpu context so it could get memory
this time and compress the data again, copies it to the memory space.In this scenario, zram assumes the data should never be changed
but it is not true unless stable page supports. So, If the data is
changed under us, zram can make buffer overrun because second
compression size could be bigger than one we got in previous trial
and blindly, copy bigger size object to smaller buffer which is
buffer overrun. The overrun breaks zsmalloc free object chaining
so system goes crash like above.I think below is same problem.
https://bugzilla.suse.com/show_bug.cgi?id=997574Unfortunately, reuse_swap_page should be atomic so that we cannot wait on
writeback in there so the approach in this patch is simply return false if
we found it needs stable page. Although it increases memory footprint
temporarily, it happens rarely and it should be reclaimed easily althoug
it happened. Also, It would be better than waiting of IO completion,
which is critial path for application latency.Fixes: da9556a2367c ("zram: user per-cpu compression streams")
Link: http://lkml.kernel.org/r/20161120233015.GA14113@bbox
Link: http://lkml.kernel.org/r/1482366980-3782-2-git-send-email-minchan@kernel.org
Signed-off-by: Minchan Kim
Acked-by: Hugh Dickins
Cc: Sergey Senozhatsky
Cc: Darrick J. Wong
Cc: Takashi Iwai
Cc: Hyeoncheol Lee
Cc:
Cc: Sangseok Lee
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
Signed-off-by: Greg Kroah-Hartman -
commit b4536f0c829c8586544c94735c343f9b5070bd01 upstream.
Nils Holland and Klaus Ethgen have reported unexpected OOM killer
invocations with 32b kernel starting with 4.8 kernelskworker/u4:5 invoked oom-killer: gfp_mask=0x2400840(GFP_NOFS|__GFP_NOFAIL), nodemask=0, order=0, oom_score_adj=0
kworker/u4:5 cpuset=/ mems_allowed=0
CPU: 1 PID: 2603 Comm: kworker/u4:5 Not tainted 4.9.0-gentoo #2
[...]
Mem-Info:
active_anon:58685 inactive_anon:90 isolated_anon:0
active_file:274324 inactive_file:281962 isolated_file:0
unevictable:0 dirty:649 writeback:0 unstable:0
slab_reclaimable:40662 slab_unreclaimable:17754
mapped:7382 shmem:202 pagetables:351 bounce:0
free:206736 free_pcp:332 free_cma:0
Node 0 active_anon:234740kB inactive_anon:360kB active_file:1097296kB inactive_file:1127848kB unevictable:0kB isolated(anon):0kB isolated(file):0kB mapped:29528kB dirty:2596kB writeback:0kB shmem:0kB shmem_thp: 0kB shmem_pmdmapped: 184320kB anon_thp: 808kB writeback_tmp:0kB unstable:0kB pages_scanned:0 all_unreclaimable? no
DMA free:3952kB min:788kB low:984kB high:1180kB active_anon:0kB inactive_anon:0kB active_file:7316kB inactive_file:0kB unevictable:0kB writepending:96kB present:15992kB managed:15916kB mlocked:0kB slab_reclaimable:3200kB slab_unreclaimable:1408kB kernel_stack:0kB pagetables:0kB bounce:0kB free_pcp:0kB local_pcp:0kB free_cma:0kB
lowmem_reserve[]: 0 813 3474 3474
Normal free:41332kB min:41368kB low:51708kB high:62048kB active_anon:0kB inactive_anon:0kB active_file:532748kB inactive_file:44kB unevictable:0kB writepending:24kB present:897016kB managed:836248kB mlocked:0kB slab_reclaimable:159448kB slab_unreclaimable:69608kB kernel_stack:1112kB pagetables:1404kB bounce:0kB free_pcp:528kB local_pcp:340kB free_cma:0kB
lowmem_reserve[]: 0 0 21292 21292
HighMem free:781660kB min:512kB low:34356kB high:68200kB active_anon:234740kB inactive_anon:360kB active_file:557232kB inactive_file:1127804kB unevictable:0kB writepending:2592kB present:2725384kB managed:2725384kB mlocked:0kB slab_reclaimable:0kB slab_unreclaimable:0kB kernel_stack:0kB pagetables:0kB bounce:0kB free_pcp:800kB local_pcp:608kB free_cma:0kBthe oom killer is clearly pre-mature because there there is still a lot
of page cache in the zone Normal which should satisfy this lowmem
request. Further debugging has shown that the reclaim cannot make any
forward progress because the page cache is hidden in the active list
which doesn't get rotated because inactive_list_is_low is not memcg
aware.The code simply subtracts per-zone highmem counters from the respective
memcg's lru sizes which doesn't make any sense. We can simply end up
always seeing the resulting active and inactive counts 0 and return
false. This issue is not limited to 32b kernels but in practice the
effect on systems without CONFIG_HIGHMEM would be much harder to notice
because we do not invoke the OOM killer for allocations requests
targeting < ZONE_NORMAL.Fix the issue by tracking per zone lru page counts in mem_cgroup_per_node
and subtract per-memcg highmem counts when memcg is enabled. Introduce
helper lruvec_zone_lru_size which redirects to either zone counters or
mem_cgroup_get_zone_lru_size when appropriate.We are losing empty LRU but non-zero lru size detection introduced by
ca707239e8a7 ("mm: update_lru_size warn and reset bad lru_size") because
of the inherent zone vs. node discrepancy.Fixes: f8d1a31163fc ("mm: consider whether to decivate based on eligible zones inactive ratio")
Link: http://lkml.kernel.org/r/20170104100825.3729-1-mhocko@kernel.org
Signed-off-by: Michal Hocko
Reported-by: Nils Holland
Tested-by: Nils Holland
Reported-by: Klaus Ethgen
Acked-by: Minchan Kim
Acked-by: Mel Gorman
Acked-by: Johannes Weiner
Reviewed-by: Vladimir Davydov
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
Signed-off-by: Greg Kroah-Hartman -
commit 20f664aabeb88d582b623a625f83b0454fa34f07 upstream.
Andreas reported [1] made a test in jemalloc hang in THP mode in arm64:
http://lkml.kernel.org/r/mvmmvfy37g1.fsf@hawking.suse.de
The problem is currently page fault handler doesn't supports dirty bit
emulation of pmd for non-HW dirty-bit architecture so that application
stucks until VM marked the pmd dirty.How the emulation work depends on the architecture. In case of arm64,
when it set up pte firstly, it sets pte PTE_RDONLY to get a chance to
mark the pte dirty via triggering page fault when store access happens.
Once the page fault occurs, VM marks the pmd dirty and arch code for
setting pmd will clear PTE_RDONLY for application to proceed.IOW, if VM doesn't mark the pmd dirty, application hangs forever by
repeated fault(i.e., store op but the pmd is PTE_RDONLY).This patch enables pmd dirty-bit emulation for those architectures.
[1] b8d3c4c3009d, mm/huge_memory.c: don't split THP page when MADV_FREE syscall is called
Fixes: b8d3c4c3009d ("mm/huge_memory.c: don't split THP page when MADV_FREE syscall is called")
Link: http://lkml.kernel.org/r/1482506098-6149-1-git-send-email-minchan@kernel.org
Signed-off-by: Minchan Kim
Reported-by: Andreas Schwab
Tested-by: Andreas Schwab
Acked-by: Kirill A. Shutemov
Acked-by: Michal Hocko
Cc: Jason Evans
Cc: Will Deacon
Cc: Catalin Marinas
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
Signed-off-by: Greg Kroah-Hartman -
commit 965d004af54088d138f806d04d803fb60d441986 upstream.
Currently in DAX if we have three read faults on the same hole address we
can end up with the following:Thread 0 Thread 1 Thread 2
-------- -------- --------
dax_iomap_fault
grab_mapping_entry
lock_slot
dax_iomap_fault
grab_mapping_entry
get_unlocked_mapping_entry
dax_iomap_fault
grab_mapping_entry
get_unlocked_mapping_entry
dax_load_hole
find_or_create_page
...
page_cache_tree_insert
dax_wake_mapping_entry_waiter
__radix_tree_replace
get_page
lock_page
...
put_locked_mapping_entry
unlock_page
put_pageThe crux of the problem is that once we insert a 4k zero page, all
locking from then on is done in terms of that 4k zero page and any
additional threads sleeping on the empty DAX entry will never be woken.Fix this by waking all sleepers when we replace the DAX radix tree entry
with a 4k zero page. This will allow all sleeping threads to
successfully transition from locking based on the DAX empty entry to
locking on the 4k zero page.With the test case reported by Xiong this happens very regularly in my
test setup, with some runs resulting in 9+ threads in this deadlocked
state. With this fix I've been able to run that same test dozens of
times in a loop without issue.Fixes: ac401cc78242 ("dax: New fault locking")
Link: http://lkml.kernel.org/r/1483479365-13607-1-git-send-email-ross.zwisler@linux.intel.com
Signed-off-by: Ross Zwisler
Reported-by: Xiong Zhou
Reviewed-by: Jan Kara
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
Signed-off-by: Greg Kroah-Hartman
12 Jan, 2017
4 commits
-
commit 6afcf8ef0ca0a69d014f8edb613d94821f0ae700 upstream.
Since commit bda807d44454 ("mm: migrate: support non-lru movable page
migration") isolate_migratepages_block) can isolate !PageLRU pages which
would acct_isolated account as NR_ISOLATED_*. Accounting these non-lru
pages NR_ISOLATED_{ANON,FILE} doesn't make any sense and it can misguide
heuristics based on those counters such as pgdat_reclaimable_pages resp.
too_many_isolated which would lead to unexpected stalls during the
direct reclaim without any good reason. Note that
__alloc_contig_migrate_range can isolate a lot of pages at once.On mobile devices such as 512M ram android Phone, it may use a big zram
swap. In some cases zram(zsmalloc) uses too many non-lru but
migratedable pages, such as:MemTotal: 468148 kB
Normal free:5620kB
Free swap:4736kB
Total swap:409596kB
ZRAM: 164616kB(zsmalloc non-lru pages)
active_anon:60700kB
inactive_anon:60744kB
active_file:34420kB
inactive_file:37532kBFix this by only accounting lru pages to NR_ISOLATED_* in
isolate_migratepages_block right after they were isolated and we still
know they were on LRU. Drop acct_isolated because it is called after
the fact and we've lost that information. Batching per-cpu counter
doesn't make much improvement anyway. Also make sure that we uncharge
only LRU pages when putting them back on the LRU in
putback_movable_pages resp. when unmap_and_move migrates the page.[mhocko@suse.com: replace acct_isolated() with direct counting]
Fixes: bda807d44454 ("mm: migrate: support non-lru movable page migration")
Link: http://lkml.kernel.org/r/20161019080240.9682-1-mhocko@kernel.org
Signed-off-by: Ming Ling
Signed-off-by: Michal Hocko
Acked-by: Minchan Kim
Acked-by: Vlastimil Babka
Cc: Mel Gorman
Cc: Joonsoo Kim
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
Signed-off-by: Greg Kroah-Hartman -
commit 59749e6ce53735d8b696763742225f126e94603f upstream.
The radix tree counts valid entries in each tree node. Entries stored
in the tree cannot be removed by simpling storing NULL in the slot or
the internal counters will be off and the node never gets freed again.When collapsing a shmem page fails, restore the holes that were filled
with radix_tree_insert() with a proper radix tree deletion.Fixes: f3f0e1d2150b ("khugepaged: add support of collapse for tmpfs/shmem pages")
Link: http://lkml.kernel.org/r/20161117191138.22769-3-hannes@cmpxchg.org
Signed-off-by: Johannes Weiner
Reported-by: Jan Kara
Acked-by: Kirill A. Shutemov
Reviewed-by: Jan Kara
Cc: Hugh Dickins
Cc: Matthew Wilcox
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
Signed-off-by: Greg Kroah-Hartman -
commit 91a45f71078a6569ec3ca5bef74e1ab58121d80e upstream.
Patch series "mm: workingset: radix tree subtleties & single-page file
refaults", v3.This is another revision of the radix tree / workingset patches based on
feedback from Jan and Kirill.This is a follow-up to d3798ae8c6f3 ("mm: filemap: don't plant shadow
entries without radix tree node"). That patch fixed an issue that was
caused mainly by the page cache sneaking special shadow page entries
into the radix tree and relying on subtleties in the radix tree code to
make that work. The fix also had to stop tracking refaults for
single-page files because shadow pages stored as direct pointers in
radix_tree_root->rnode weren't properly handled during tree extension.These patches make the radix tree code explicitely support and track
such special entries, to eliminate the subtleties and to restore the
thrash detection for single-page files.This patch (of 9):
When a radix tree iteration drops the tree lock, another thread might
swoop in and free the node holding the current slot. The iteration
needs to do another tree lookup from the current index to continue.[kirill.shutemov@linux.intel.com: re-lookup for replacement]
Fixes: f3f0e1d2150b ("khugepaged: add support of collapse for tmpfs/shmem pages")
Link: http://lkml.kernel.org/r/20161117191138.22769-2-hannes@cmpxchg.org
Signed-off-by: Johannes Weiner
Acked-by: Kirill A. Shutemov
Reviewed-by: Jan Kara
Cc: Hugh Dickins
Cc: Matthew Wilcox
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
Signed-off-by: Greg Kroah-Hartman -
commit 3999f52e3198e76607446ab1a4610c1ddc406c56 upstream.
We cannot use the pte value used in set_pte_at for pte_same comparison,
because archs like ppc64, filter/add new pte flag in set_pte_at.
Instead fetch the pte value inside hugetlb_cow. We are comparing pte
value to make sure the pte didn't change since we dropped the page table
lock. hugetlb_cow get called with page table lock held, and we can take
a copy of the pte value before we drop the page table lock.With hugetlbfs, we optimize the MAP_PRIVATE write fault path with no
previous mapping (huge_pte_none entries), by forcing a cow in the fault
path. This avoid take an addition fault to covert a read-only mapping
to read/write. Here we were comparing a recently instantiated pte (via
set_pte_at) to the pte values from linux page table. As explained above
on ppc64 such pte_same check returned wrong result, resulting in us
taking an additional fault on ppc64.Fixes: 6a119eae942c ("powerpc/mm: Add a _PAGE_PTE bit")
Link: http://lkml.kernel.org/r/20161018154245.18023-1-aneesh.kumar@linux.vnet.ibm.com
Signed-off-by: Aneesh Kumar K.V
Reported-by: Jan Stancek
Acked-by: Hillf Danton
Cc: Mike Kravetz
Cc: Scott Wood
Cc: Michael Ellerman
Cc: Kirill A. Shutemov
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
Signed-off-by: Greg Kroah-Hartman
06 Jan, 2017
5 commits
-
commit a6de734bc002fe2027ccc074fbbd87d72957b7a4 upstream.
Vlastimil Babka pointed out that commit 479f854a207c ("mm, page_alloc:
defer debugging checks of pages allocated from the PCP") will allow the
per-cpu list counter to be out of sync with the per-cpu list contents if
a struct page is corrupted.The consequence is an infinite loop if the per-cpu lists get fully
drained by free_pcppages_bulk because all the lists are empty but the
count is positive. The infinite loop occurs heredo {
batch_free++;
if (++migratetype == MIGRATE_PCPTYPES)
migratetype = 0;
list = &pcp->lists[migratetype];
} while (list_empty(list));What the user sees is a bad page warning followed by a soft lockup with
interrupts disabled in free_pcppages_bulk().This patch keeps the accounting in sync.
Fixes: 479f854a207c ("mm, page_alloc: defer debugging checks of pages allocated from the PCP")
Link: http://lkml.kernel.org/r/20161202112951.23346-2-mgorman@techsingularity.net
Signed-off-by: Mel Gorman
Acked-by: Vlastimil Babka
Acked-by: Michal Hocko
Acked-by: Hillf Danton
Cc: Christoph Lameter
Cc: Johannes Weiner
Cc: Jesper Dangaard Brouer
Cc: Joonsoo Kim
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
Signed-off-by: Greg Kroah-Hartman -
commit 5f33a0803bbd781de916f5c7448cbbbbc763d911 upstream.
Our system uses significantly more slab memory with memcg enabled with
the latest kernel. With 3.10 kernel, slab uses 2G memory, while with
4.6 kernel, 6G memory is used. The shrinker has problem. Let's see we
have two memcg for one shrinker. In do_shrink_slab:1. Check cg1. nr_deferred = 0, assume total_scan = 700. batch size
is 1024, then no memory is freed. nr_deferred = 7002. Check cg2. nr_deferred = 700. Assume freeable = 20, then
total_scan = 10 or 40. Let's assume it's 10. No memory is freed.
nr_deferred = 10.The deferred share of cg1 is lost in this case. kswapd will free no
memory even run above steps again and again.The fix makes sure one memcg's deferred share isn't lost.
Link: http://lkml.kernel.org/r/2414be961b5d25892060315fbb56bb19d81d0c07.1476227351.git.shli@fb.com
Signed-off-by: Shaohua Li
Cc: Johannes Weiner
Cc: Michal Hocko
Cc: Vladimir Davydov
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
Signed-off-by: Greg Kroah-Hartman -
commit 84d77d3f06e7e8dea057d10e8ec77ad71f721be3 upstream.
It is the reasonable expectation that if an executable file is not
readable there will be no way for a user without special privileges to
read the file. This is enforced in ptrace_attach but if ptrace
is already attached before exec there is no enforcement for read-only
executables.As the only way to read such an mm is through access_process_vm
spin a variant called ptrace_access_vm that will fail if the
target process is not being ptraced by the current process, or
the current process did not have sufficient privileges when ptracing
began to read the target processes mm.In the ptrace implementations replace access_process_vm by
ptrace_access_vm. There remain several ptrace sites that still use
access_process_vm as they are reading the target executables
instructions (for kernel consumption) or register stacks. As such it
does not appear necessary to add a permission check to those calls.This bug has always existed in Linux.
Fixes: v1.0
Reported-by: Andy Lutomirski
Signed-off-by: "Eric W. Biederman"
Signed-off-by: Greg Kroah-Hartman -
commit d05c5f7ba164aed3db02fb188c26d0dd94f5455b upstream.
We truncated the possible read iterator to s_maxbytes in commit
c2a9737f45e2 ("vfs,mm: fix a dead loop in truncate_inode_pages_range()"),
but our end condition handling was wrong: it's not an error to try to
read at the end of the file.Reading past the end should return EOF (0), not EINVAL.
See for example
https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1649342
http://lists.gnu.org/archive/html/bug-coreutils/2016-12/msg00008.htmlwhere a md5sum of a maximally sized file fails because the final read is
exactly at s_maxbytes.Fixes: c2a9737f45e2 ("vfs,mm: fix a dead loop in truncate_inode_pages_range()")
Reported-by: Joseph Salisbury
Cc: Wei Fang
Cc: Christoph Hellwig
Cc: Dave Chinner
Cc: Al Viro
Cc: Andrew Morton
Signed-off-by: Linus Torvalds
Signed-off-by: Greg Kroah-Hartman -
commit bfedb589252c01fa505ac9f6f2a3d5d68d707ef4 upstream.
During exec dumpable is cleared if the file that is being executed is
not readable by the user executing the file. A bug in
ptrace_may_access allows reading the file if the executable happens to
enter into a subordinate user namespace (aka clone(CLONE_NEWUSER),
unshare(CLONE_NEWUSER), or setns(fd, CLONE_NEWUSER).This problem is fixed with only necessary userspace breakage by adding
a user namespace owner to mm_struct, captured at the time of exec, so
it is clear in which user namespace CAP_SYS_PTRACE must be present in
to be able to safely give read permission to the executable.The function ptrace_may_access is modified to verify that the ptracer
has CAP_SYS_ADMIN in task->mm->user_ns instead of task->cred->user_ns.
This ensures that if the task changes it's cred into a subordinate
user namespace it does not become ptraceable.The function ptrace_attach is modified to only set PT_PTRACE_CAP when
CAP_SYS_PTRACE is held over task->mm->user_ns. The intent of
PT_PTRACE_CAP is to be a flag to note that whatever permission changes
the task might go through the tracer has sufficient permissions for
it not to be an issue. task->cred->user_ns is always the same
as or descendent of mm->user_ns. Which guarantees that having
CAP_SYS_PTRACE over mm->user_ns is the worst case for the tasks
credentials.To prevent regressions mm->dumpable and mm->user_ns are not considered
when a task has no mm. As simply failing ptrace_may_attach causes
regressions in privileged applications attempting to read things
such as /proc//statAcked-by: Kees Cook
Tested-by: Cyrill Gorcunov
Fixes: 8409cca70561 ("userns: allow ptrace from non-init user namespaces")
Signed-off-by: "Eric W. Biederman"
Signed-off-by: Greg Kroah-Hartman
07 Dec, 2016
1 commit
-
The shmem hole punching with fallocate(FALLOC_FL_PUNCH_HOLE) does not
want to race with generating new pages by faulting them in.However, the wait-queue used to delay the page faulting has a serious
problem: the wait queue head (in shmem_fallocate()) is allocated on the
stack, and the code expects that "wake_up_all()" will make sure that all
the queue entries are gone before the stack frame is de-allocated.And that is not at all necessarily the case.
Yes, a normal wake-up sequence will remove the wait-queue entry that
caused the wakeup (see "autoremove_wake_function()"), but the key
wording there is "that caused the wakeup". When there are multiple
possible wakeup sources, the wait queue entry may well stay around.And _particularly_ in a page fault path, we may be faulting in new pages
from user space while we also have other things going on, and there may
well be other pending wakeups.So despite the "wake_up_all()", it's not at all guaranteed that all list
entries are removed from the wait queue head on the stack.Fix this by introducing a new wakeup function that removes the list
entry unconditionally, even if the target process had already woken up
for other reasons. Use that "synchronous" function to set up the
waiters in shmem_fault().This problem has never been seen in the wild afaik, but Dave Jones has
reported it on and off while running trinity. We thought we fixed the
stack corruption with the blk-mq rq_list locking fix (commit
7fe311302f7d: "blk-mq: update hardware and software queues for sleeping
alloc"), but it turns out there was _another_ stack corruptor hiding
in the trinity runs.Vegard Nossum (also running trinity) was able to trigger this one fairly
consistently, and made us look once again at the shmem code due to the
faults often being in that area.Reported-and-tested-by: Vegard Nossum .
Reported-by: Dave Jones
Signed-off-by: Linus Torvalds
03 Dec, 2016
2 commits
-
Boris Zhmurov has reported RCU stalls during the kswapd reclaim:
INFO: rcu_sched detected stalls on CPUs/tasks:
23-...: (22 ticks this GP) idle=92f/140000000000000/0 softirq=2638404/2638404 fqs=23
(detected by 4, t=6389 jiffies, g=786259, c=786258, q=42115)
Task dump for CPU 23:
kswapd1 R running task 0 148 2 0x00000008
Call Trace:
shrink_node+0xd2/0x2f0
kswapd+0x2cb/0x6a0
mem_cgroup_shrink_node+0x160/0x160
kthread+0xbd/0xe0
__switch_to+0x1fa/0x5c0
ret_from_fork+0x1f/0x40
kthread_create_on_node+0x180/0x180a closer code inspection has shown that we might indeed miss all the
scheduling points in the reclaim path if no pages can be isolated from
the LRU list. This is a pathological case but other reports from Donald
Buczek have shown that we might indeed hit such a path:clusterd-989 [009] .... 118023.654491: mm_vmscan_direct_reclaim_end: nr_reclaimed=193
kswapd1-86 [001] dN.. 118023.987475: mm_vmscan_lru_isolate: isolate_mode=0 classzone=0 order=0 nr_requested=32 nr_scanned=4239830 nr_taken=0 file=1
kswapd1-86 [001] dN.. 118024.320968: mm_vmscan_lru_isolate: isolate_mode=0 classzone=0 order=0 nr_requested=32 nr_scanned=4239844 nr_taken=0 file=1
kswapd1-86 [001] dN.. 118024.654375: mm_vmscan_lru_isolate: isolate_mode=0 classzone=0 order=0 nr_requested=32 nr_scanned=4239858 nr_taken=0 file=1
kswapd1-86 [001] dN.. 118024.987036: mm_vmscan_lru_isolate: isolate_mode=0 classzone=0 order=0 nr_requested=32 nr_scanned=4239872 nr_taken=0 file=1
kswapd1-86 [001] dN.. 118025.319651: mm_vmscan_lru_isolate: isolate_mode=0 classzone=0 order=0 nr_requested=32 nr_scanned=4239886 nr_taken=0 file=1
kswapd1-86 [001] dN.. 118025.652248: mm_vmscan_lru_isolate: isolate_mode=0 classzone=0 order=0 nr_requested=32 nr_scanned=4239900 nr_taken=0 file=1
kswapd1-86 [001] dN.. 118025.984870: mm_vmscan_lru_isolate: isolate_mode=0 classzone=0 order=0 nr_requested=32 nr_scanned=4239914 nr_taken=0 file=1
[...]
kswapd1-86 [001] dN.. 118084.274403: mm_vmscan_lru_isolate: isolate_mode=0 classzone=0 order=0 nr_requested=32 nr_scanned=4241133 nr_taken=0 file=1this is minute long snapshot which didn't take a single page from the
LRU. It is not entirely clear why only 1303 pages have been scanned
during that time (maybe there was a heavy IRQ activity interfering).In any case it looks like we can really hit long periods without
scheduling on non preemptive kernels so an explicit cond_resched() in
shrink_node_memcg which is independent on the reclaim operation is due.Link: http://lkml.kernel.org/r/20161202095841.16648-1-mhocko@kernel.org
Signed-off-by: Michal Hocko
Reported-by: Boris Zhmurov
Tested-by: Boris Zhmurov
Reported-by: Donald Buczek
Reported-by: "Christopher S. Aker"
Reported-by: Paul Menzel
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
Commit 0a6b76dd23fa ("mm: workingset: make shadow node shrinker memcg
aware") has made the workingset shadow nodes shrinker memcg aware. The
implementation is not correct though because memcg_kmem_enabled() might
become true while we are doing a global reclaim when the sc->memcg might
be NULL which is exactly what Marek has seen:BUG: unable to handle kernel NULL pointer dereference at 0000000000000400
IP: [] mem_cgroup_node_nr_lru_pages+0x20/0x40
PGD 0
Oops: 0000 [#1] SMP
CPU: 0 PID: 60 Comm: kswapd0 Tainted: G O 4.8.10-12.pvops.qubes.x86_64 #1
task: ffff880011863b00 task.stack: ffff880011868000
RIP: mem_cgroup_node_nr_lru_pages+0x20/0x40
RSP: e02b:ffff88001186bc70 EFLAGS: 00010293
RAX: 0000000000000000 RBX: ffff88001186bd20 RCX: 0000000000000002
RDX: 000000000000000c RSI: 0000000000000000 RDI: 0000000000000000
RBP: ffff88001186bc70 R08: 28f5c28f5c28f5c3 R09: 0000000000000000
R10: 0000000000006c34 R11: 0000000000000333 R12: 00000000000001f6
R13: ffffffff81c6f6a0 R14: 0000000000000000 R15: 0000000000000000
FS: 0000000000000000(0000) GS:ffff880013c00000(0000) knlGS:ffff880013d00000
CS: e033 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000400 CR3: 00000000122f2000 CR4: 0000000000042660
Call Trace:
count_shadow_nodes+0x9a/0xa0
shrink_slab.part.42+0x119/0x3e0
shrink_node+0x22c/0x320
kswapd+0x32c/0x700
kthread+0xd8/0xf0
ret_from_fork+0x1f/0x40
Code: 66 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 3b 35 dd eb b1 00 55 48 89 e5 73 2c 89 d2 31 c9 31 c0 4c 63 ce 48 0f a3 ca 73 13 8b b4 cf 00 04 00 00 41 89 c8 4a 03 84 c6 80 00 00 00 83 c1
RIP mem_cgroup_node_nr_lru_pages+0x20/0x40
RSP
CR2: 0000000000000400
---[ end trace 100494b9edbdfc4d ]---This patch fixes the issue by checking sc->memcg rather than
memcg_kmem_enabled() which is sufficient because shrink_slab makes sure
that only memcg aware shrinkers will get non-NULL memcgs and only if
memcg_kmem_enabled is true.Fixes: 0a6b76dd23fa ("mm: workingset: make shadow node shrinker memcg aware")
Link: http://lkml.kernel.org/r/20161201132156.21450-1-mhocko@kernel.org
Signed-off-by: Michal Hocko
Reported-by: Marek Marczykowski-Górecki
Tested-by: Marek Marczykowski-Górecki
Acked-by: Vladimir Davydov
Acked-by: Johannes Weiner
Acked-by: Balbir Singh
Cc: [4.6+]
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
01 Dec, 2016
5 commits
-
Hugetlb pages have ->index in size of the huge pages (PMD_SIZE or
PUD_SIZE), not in PAGE_SIZE as other types of pages. This means we
cannot user page_to_pgoff() to check whether we've got the right page
for the radix-tree index.Let's introduce page_to_index() which would return radix-tree index for
given page.We will be able to get rid of this once hugetlb will be switched to
multi-order entries.Fixes: fc127da085c2 ("truncate: handle file thp")
Link: http://lkml.kernel.org/r/20161123093053.mjbnvn5zwxw5e6lk@black.fi.intel.com
Signed-off-by: Kirill A. Shutemov
Reported-by: Doug Nelson
Tested-by: Doug Nelson
Reviewed-by: Naoya Horiguchi
Cc: [4.8+]
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
Gcc revision 241896 implements use-after-scope detection. Will be
available in gcc 7. Support it in KASAN.Gcc emits 2 new callbacks to poison/unpoison large stack objects when
they go in/out of scope. Implement the callbacks and add a test.[dvyukov@google.com: v3]
Link: http://lkml.kernel.org/r/1479998292-144502-1-git-send-email-dvyukov@google.com
Link: http://lkml.kernel.org/r/1479226045-145148-1-git-send-email-dvyukov@google.com
Signed-off-by: Dmitry Vyukov
Acked-by: Andrey Ryabinin
Cc: Alexander Potapenko
Cc: [4.0+]
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
kasan_global struct is part of compiler/runtime ABI. gcc revision
241983 has added a new field to kasan_global struct. Update kernel
definition of kasan_global struct to include the new field.Without this patch KASAN is broken with gcc 7.
Link: http://lkml.kernel.org/r/1479219743-28682-1-git-send-email-dvyukov@google.com
Signed-off-by: Dmitry Vyukov
Acked-by: Andrey Ryabinin
Cc: Alexander Potapenko
Cc: [4.0+]
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
The following program triggers BUG() in munlock_vma_pages_range():
// autogenerated by syzkaller (http://github.com/google/syzkaller)
#includeint main()
{
mmap((void*)0x20105000ul, 0xc00000ul, 0x2ul, 0x2172ul, -1, 0);
mremap((void*)0x201fd000ul, 0x4000ul, 0xc00000ul, 0x3ul, 0x203f0000ul);
return 0;
}The test-case constructs the situation when munlock_vma_pages_range()
finds PTE-mapped THP-head in the middle of page table and, by mistake,
skips HPAGE_PMD_NR pages after that.As result, on the next iteration it hits the middle of PMD-mapped THP
and gets upset seeing mlocked tail page.The solution is only skip HPAGE_PMD_NR pages if the THP was mlocked
during munlock_vma_page(). It would guarantee that the page is
PMD-mapped as we never mlock PTE-mapeed THPs.Fixes: e90309c9f772 ("thp: allow mlocked THP again")
Link: http://lkml.kernel.org/r/20161115132703.7s7rrgmwttegcdh4@black.fi.intel.com
Signed-off-by: Kirill A. Shutemov
Reported-by: Dmitry Vyukov
Cc: Konstantin Khlebnikov
Cc: Andrey Ryabinin
Cc: syzkaller
Cc: Andrea Arcangeli
Cc: [4.5+]
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
Commit b46e756f5e47 ("thp: extract khugepaged from mm/huge_memory.c")
moved code from huge_memory.c to khugepaged.c. Some of this code should
be compiled only when CONFIG_SYSFS is enabled but the condition around
this code was not moved into khugepaged.c.The result is a compilation error when CONFIG_SYSFS is disabled:
mm/built-in.o: In function `khugepaged_defrag_store': khugepaged.c:(.text+0x2d095): undefined reference to `single_hugepage_flag_store'
mm/built-in.o: In function `khugepaged_defrag_show': khugepaged.c:(.text+0x2d0ab): undefined reference to `single_hugepage_flag_show'This commit adds the #ifdef CONFIG_SYSFS around the code related to
sysfs.Link: http://lkml.kernel.org/r/20161114203448.24197-1-jeremy.lefaure@lse.epita.fr
Signed-off-by: Jérémy Lefaure
Acked-by: Kirill A. Shutemov
Acked-by: Hillf Danton
Cc:
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
30 Nov, 2016
1 commit
-
Linus found there still is a race in mremap after commit 5d1904204c99
("mremap: fix race between mremap() and page cleanning").As described by Linus:
"the issue is that another thread might make the pte be dirty (in the
hardware walker, so no locking of ours will make any difference)
*after* we checked whether it was dirty, but *before* we removed it
from the page tables"Fix it by moving the check after we removed it from the page table.
Suggested-by: Linus Torvalds
Signed-off-by: Aaron Lu
Signed-off-by: Linus Torvalds
18 Nov, 2016
1 commit
-
Prior to 3.15, there was a race between zap_pte_range() and
page_mkclean() where writes to a page could be lost. Dave Hansen
discovered by inspection that there is a similar race between
move_ptes() and page_mkclean().We've been able to reproduce the issue by enlarging the race window with
a msleep(), but have not been able to hit it without modifying the code.
So, we think it's a real issue, but is difficult or impossible to hit in
practice.The zap_pte_range() issue is fixed by commit 1cf35d47712d("mm: split
'tlb_flush_mmu()' into tlb flushing and memory freeing parts"). And
this patch is to fix the race between page_mkclean() and mremap().Here is one possible way to hit the race: suppose a process mmapped a
file with READ | WRITE and SHARED, it has two threads and they are bound
to 2 different CPUs, e.g. CPU1 and CPU2. mmap returned X, then thread
1 did a write to addr X so that CPU1 now has a writable TLB for addr X
on it. Thread 2 starts mremaping from addr X to Y while thread 1
cleaned the page and then did another write to the old addr X again.
The 2nd write from thread 1 could succeed but the value will get lost.thread 1 thread 2
(bound to CPU1) (bound to CPU2)1: write 1 to addr X to get a
writeable TLB on this CPU2: mremap starts
3: move_ptes emptied PTE for addr X
and setup new PTE for addr Y and
then dropped PTL for X and Y4: page laundering for N by doing
fadvise FADV_DONTNEED. When done,
pageframe N is deemed clean.5: *write 2 to addr X
6: tlb flush for addr X
7: munmap (Y, pagesize) to make the
page unmapped8: fadvise with FADV_DONTNEED again
to kick the page off the pagecache9: pread the page from file to verify
the value. If 1 is there, it means
we have lost the written 2.*the write may or may not cause segmentation fault, it depends on
if the TLB is still on the CPU.Please note that this is only one specific way of how the race could
occur, it didn't mean that the race could only occur in exact the above
config, e.g. more than 2 threads could be involved and fadvise() could
be done in another thread, etc.For anonymous pages, they could race between mremap() and page reclaim:
THP: a huge PMD is moved by mremap to a new huge PMD, then the new huge
PMD gets unmapped/splitted/pagedout before the flush tlb happened for
the old huge PMD in move_page_tables() and we could still write data to
it. The normal anonymous page has similar situation.To fix this, check for any dirty PTE in move_ptes()/move_huge_pmd() and
if any, did the flush before dropping the PTL. If we did the flush for
every move_ptes()/move_huge_pmd() call then we do not need to do the
flush in move_pages_tables() for the whole range. But if we didn't, we
still need to do the whole range flush.Alternatively, we can track which part of the range is flushed in
move_ptes()/move_huge_pmd() and which didn't to avoid flushing the whole
range in move_page_tables(). But that would require multiple tlb
flushes for the different sub-ranges and should be less efficient than
the single whole range flush.KBuild test on my Sandybridge desktop doesn't show any noticeable change.
v4.9-rc4:
real 5m14.048s
user 32m19.800s
sys 4m50.320sWith this commit:
real 5m13.888s
user 32m19.330s
sys 4m51.200sReported-by: Dave Hansen
Signed-off-by: Aaron Lu
Signed-off-by: Linus Torvalds
12 Nov, 2016
2 commits
-
Limit the number of kmemleak false positives by including
.data.ro_after_init in memory scanning. To achieve this we need to add
symbols for start and end of the section to the linker scripts.The problem was been uncovered by commit 56989f6d8568 ("genetlink: mark
families as __ro_after_init").Link: http://lkml.kernel.org/r/1478274173-15218-1-git-send-email-jakub.kicinski@netronome.com
Reviewed-by: Catalin Marinas
Signed-off-by: Jakub Kicinski
Cc: Arnd Bergmann
Cc: Cong Wang
Cc: Johannes Berg
Cc: Martin Schwidefsky
Cc: Heiko Carstens
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
While testing OBJFREELIST_SLAB integration with pagealloc, we found a
bug where kmem_cache(sys) would be created with both CFLGS_OFF_SLAB &
CFLGS_OBJFREELIST_SLAB. When it happened, critical allocations needed
for loading drivers or creating new caches will fail.The original kmem_cache is created early making OFF_SLAB not possible.
When kmem_cache(sys) is created, OFF_SLAB is possible and if pagealloc
is enabled it will try to enable it first under certain conditions.
Given kmem_cache(sys) reuses the original flag, you can have both flags
at the same time resulting in allocation failures and odd behaviors.This fix discards allocator specific flags from memcg before calling
create_cache.The bug exists since 4.6-rc1 and affects testing debug pagealloc
configurations.Fixes: b03a017bebc4 ("mm/slab: introduce new slab management type, OBJFREELIST_SLAB")
Link: http://lkml.kernel.org/r/1478553075-120242-1-git-send-email-thgarnie@google.com
Signed-off-by: Greg Thelen
Signed-off-by: Thomas Garnier
Tested-by: Thomas Garnier
Acked-by: Christoph Lameter
Cc: Pekka Enberg
Cc: David Rientjes
Cc: Joonsoo Kim
Cc: Vladimir Davydov
Cc: Michal Hocko
Cc: Johannes Weiner
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
