16 Aug, 2010
1 commit
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This commit makes the stack guard page somewhat less visible to user
space. It does this by:- not showing the guard page in /proc//maps
It looks like lvm-tools will actually read /proc/self/maps to figure
out where all its mappings are, and effectively do a specialized
"mlockall()" in user space. By not showing the guard page as part of
the mapping (by just adding PAGE_SIZE to the start for grows-up
pages), lvm-tools ends up not being aware of it.- by also teaching the _real_ mlock() functionality not to try to lock
the guard page.That would just expand the mapping down to create a new guard page,
so there really is no point in trying to lock it in place.It would perhaps be nice to show the guard page specially in
/proc//maps (or at least mark grow-down segments some way), but
let's not open ourselves up to more breakage by user space from programs
that depends on the exact deails of the 'maps' file.Special thanks to Henrique de Moraes Holschuh for diving into lvm-tools
source code to see what was going on with the whole new warning.Reported-and-tested-by: François Valenduc
Cc: stable@kernel.org
Signed-off-by: Linus Torvalds
15 Aug, 2010
2 commits
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Remove leading /** from non-kernel-doc function comments to prevent
kernel-doc warnings.Signed-off-by: Randy Dunlap
Signed-off-by: Linus Torvalds -
We do in fact need to unmap the page table _before_ doing the whole
stack guard page logic, because if it is needed (mainly 32-bit x86 with
PAE and CONFIG_HIGHPTE, but other architectures may use it too) then it
will do a kmap_atomic/kunmap_atomic.And those kmaps will create an atomic region that we cannot do
allocations in. However, the whole stack expand code will need to do
anon_vma_prepare() and vma_lock_anon_vma() and they cannot do that in an
atomic region.Now, a better model might actually be to do the anon_vma_prepare() when
_creating_ a VM_GROWSDOWN segment, and not have to worry about any of
this at page fault time. But in the meantime, this is the
straightforward fix for the issue.See https://bugzilla.kernel.org/show_bug.cgi?id=16588 for details.
Reported-by: Wylda
Reported-by: Sedat Dilek
Reported-by: Mike Pagano
Reported-by: François Valenduc
Tested-by: Ed Tomlinson
Cc: Pekka Enberg
Cc: Greg KH
Cc: stable@kernel.org
Signed-off-by: Linus Torvalds
14 Aug, 2010
2 commits
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Remove an extraneous no_printk() in mm/nommu.c that got missed when the
function got generalised from several things that used it in commit
12fdff3fc248 ("Add a dummy printk function for the maintenance of unused
printks").Without this, the following error is observed:
mm/nommu.c:41: error: conflicting types for 'no_printk'
include/linux/kernel.h:314: error: previous definition of 'no_printk' was hereReported-by: Michal Simek
Signed-off-by: David Howells
Signed-off-by: Linus Torvalds -
.. which didn't show up in my tests because it's a no-op on x86-64 and
most other architectures. But we enter the function with the last-level
page table mapped, and should unmap it at exit.Signed-off-by: Linus Torvalds
13 Aug, 2010
3 commits
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This is a rather minimally invasive patch to solve the problem of the
user stack growing into a memory mapped area below it. Whenever we fill
the first page of the stack segment, expand the segment down by one
page.Now, admittedly some odd application might _want_ the stack to grow down
into the preceding memory mapping, and so we may at some point need to
make this a process tunable (some people might also want to have more
than a single page of guarding), but let's try the minimal approach
first.Tested with trivial application that maps a single page just below the
stack, and then starts recursing. Without this, we will get a SIGSEGV
_after_ the stack has smashed the mapping. With this patch, we'll get a
nice SIGBUS just as the stack touches the page just above the mapping.Requested-by: Keith Packard
Signed-off-by: Linus Torvalds -
* 'hwpoison' of git://git.kernel.org/pub/scm/linux/kernel/git/ak/linux-mce-2.6:
hugetlb: add missing unlock in avoidcopy path in hugetlb_cow()
hwpoison: rename CONFIG
HWPOISON, hugetlb: support hwpoison injection for hugepage
HWPOISON, hugetlb: detect hwpoison in hugetlb code
HWPOISON, hugetlb: isolate corrupted hugepage
HWPOISON, hugetlb: maintain mce_bad_pages in handling hugepage error
HWPOISON, hugetlb: set/clear PG_hwpoison bits on hugepage
HWPOISON, hugetlb: enable error handling path for hugepage
hugetlb, rmap: add reverse mapping for hugepage
hugetlb: move definition of is_vm_hugetlb_page() to hugepage_inline.hFix up trivial conflicts in mm/memory-failure.c
-
* 'stable/xen-swiotlb-0.8.6' of git://git.kernel.org/pub/scm/linux/kernel/git/konrad/xen:
x86: Detect whether we should use Xen SWIOTLB.
pci-swiotlb-xen: Add glue code to setup dma_ops utilizing xen_swiotlb_* functions.
swiotlb-xen: SWIOTLB library for Xen PV guest with PCI passthrough.
xen/mmu: inhibit vmap aliases rather than trying to clear them out
vmap: add flag to allow lazy unmap to be disabled at runtime
xen: Add xen_create_contiguous_region
xen: Rename the balloon lock
xen: Allow unprivileged Xen domains to create iomap pages
xen: use _PAGE_IOMAP in ioremap to do machine mappingsFix up trivial conflicts (adding both xen swiotlb and xen pci platform
driver setup close to each other) in drivers/xen/{Kconfig,Makefile} and
include/xen/xen-ops.h
12 Aug, 2010
4 commits
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Document global_dirty_limits() and bdi_dirty_limit().
Signed-off-by: Wu Fengguang
Cc: Christoph Hellwig
Cc: Dave Chinner
Cc: Jens Axboe
Cc: Peter Zijlstra
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
Split get_dirty_limits() into global_dirty_limits()+bdi_dirty_limit(), so
that the latter can be avoided when under global dirty background
threshold (which is the normal state for most systems).Signed-off-by: Wu Fengguang
Cc: Peter Zijlstra
Cc: Christoph Hellwig
Cc: Dave Chinner
Cc: Jens Axboe
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
Reducing the number of times balance_dirty_pages calls global_page_state
reduces the cache references and so improves write performance on a
variety of workloads.'perf stats' of simple fio write tests shows the reduction in cache
access. Where the test is fio 'write,mmap,600Mb,pre_read' on AMD AthlonX2
with 3Gb memory (dirty_threshold approx 600 Mb) running each test 10
times, dropping the fasted & slowest values then taking the average &
standard deviationaverage (s.d.) in millions (10^6)
2.6.31-rc8 648.6 (14.6)
+patch 620.1 (16.5)Achieving this reduction is by dropping clip_bdi_dirty_limit as it rereads
the counters to apply the dirty_threshold and moving this check up into
balance_dirty_pages where it has already read the counters.Also by rearrange the for loop to only contain one copy of the limit tests
allows the pdflush test after the loop to use the local copies of the
counters rather than rereading them.In the common case with no throttling it now calls global_page_state 5
fewer times and bdi_stat 2 fewer.Fengguang:
This patch slightly changes behavior by replacing clip_bdi_dirty_limit()
with the explicit check (nr_reclaimable + nr_writeback >= dirty_thresh) to
avoid exceeding the dirty limit. Since the bdi dirty limit is mostly
accurate we don't need to do routinely clip. A simple dirty limit check
would be enough.The check is necessary because, in principle we should throttle everything
calling balance_dirty_pages() when we're over the total limit, as said by
Peter.We now set and clear dirty_exceeded not only based on bdi dirty limits,
but also on the global dirty limit. The global limit check is added in
place of clip_bdi_dirty_limit() for safety and not intended as a behavior
change. The bdi limits should be tight enough to keep all dirty pages
under the global limit at most time; occasional small exceeding should be
OK though. The change makes the logic more obvious: the global limit is
the ultimate goal and shall be always imposed.We may now start background writeback work based on outdated conditions.
That's safe because the bdi flush thread will (and have to) double check
the states. It reduces overall overheads because the test based on old
states still have good chance to be right.[akpm@linux-foundation.org] fix uninitialized dirty_exceeded
Signed-off-by: Richard Kennedy
Signed-off-by: Wu Fengguang
Cc: Jan Kara
Acked-by: Peter Zijlstra
Cc: Christoph Hellwig
Cc: Dave Chinner
Cc: Jens Axboe
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
Fix a fatal kernel-doc error due to a #define coming between a function's
kernel-doc notation and the function signature. (kernel-doc cannot handle
this)Signed-off-by: Randy Dunlap
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
11 Aug, 2010
23 commits
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We have zone_to_nid(). this patch convert all existing users of
zone->zone_pgdat->node_id.Signed-off-by: KOSAKI Motohiro
Acked-by: Balbir Singh
Cc: KAMEZAWA Hiroyuki
Cc: Mel Gorman
Cc: Nishimura Daisuke
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
mem_cgroup_soft_limit_reclaim() has zone, nid and zid argument. but nid
and zid can be calculated from zone. So remove it.Signed-off-by: KOSAKI Motohiro
Acked-by: KAMEZAWA Hiroyuki
Acked-by: Mel Gorman
Cc: Balbir Singh
Cc: Nishimura Daisuke
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
Currently mem_cgroup_shrink_node_zone() call shrink_zone() directly. thus
it doesn't need to initialize sc.nodemask because shrink_zone() doesn't
use it at all.Signed-off-by: KOSAKI Motohiro
Acked-by: KAMEZAWA Hiroyuki
Acked-by: Mel Gorman
Cc: Balbir Singh
Cc: Nishimura Daisuke
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
sc.nr_reclaimed and sc.nr_scanned have already been initialized few lines
above "struct scan_control sc = {}" statement.So, This patch remove this unnecessary code.
Signed-off-by: KOSAKI Motohiro
Acked-by: KAMEZAWA Hiroyuki
Cc: Balbir Singh
Cc: Mel Gorman
Cc: Nishimura Daisuke
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
Currently, mem_cgroup_shrink_node_zone() initialize sc.nr_to_reclaim as 0.
It mean shrink_zone() only scan 32 pages and immediately return even if
it doesn't reclaim any pages.This patch fixes it.
Signed-off-by: KOSAKI Motohiro
Acked-by: KAMEZAWA Hiroyuki
Acked-by: Mel Gorman
Cc: Balbir Singh
Cc: Nishimura Daisuke
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
Now, memory cgroup increments css(cgroup subsys state)'s reference count
per a charged page. And the reference count is kept until the page is
uncharged. But this has 2 bad effect.1. Because css_get/put calls atomic_inc()/dec, heavy call of them
on large smp will not scale well.
2. Because css's refcnt cannot be in a state as "ready-to-release",
cgroup's notify_on_release handler can't work with memcg.
3. css's refcnt is atomic_t, it means smaller than 32bit. Maybe too small.This has been a problem since the 1st merge of memcg.
This is a trial to remove css's refcnt per a page. Even if we remove
refcnt, pre_destroy() does enough synchronization as
- check res->usage == 0.
- check no pages on LRU.This patch removes css's refcnt per page. Even after this patch, at the
1st look, it seems css_get() is still called in try_charge().But the logic is.
- If a memcg of mm->owner is cached one, consume_stock() will work.
At success, return immediately.
- If consume_stock returns false, css_get() is called and go to
slow path which may be blocked. At the end of slow path,
css_put() is called and restart from the start if necessary.So, in the fast path, we don't call css_get() and can avoid access to
shared counter. This patch can make the most possible case fast.Here is a result of multi-threaded page fault benchmark.
[Before]
25.32% multi-fault-all [kernel.kallsyms] [k] clear_page_c
9.30% multi-fault-all [kernel.kallsyms] [k] _raw_spin_lock_irqsave
8.02% multi-fault-all [kernel.kallsyms] [k] try_get_mem_cgroup_from_mm
Signed-off-by: KAMEZAWA Hiroyuki
Cc: Daisuke Nishimura
Cc: Balbir Singh
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
When the OOM killer scans task, it check a task is under memcg or
not when it's called via memcg's context.But, as Oleg pointed out, a thread group leader may have NULL ->mm
and task_in_mem_cgroup() may do wrong decision. We have to use
find_lock_task_mm() in memcg as generic OOM-Killer does.Signed-off-by: KAMEZAWA Hiroyuki
Cc: Oleg Nesterov
Cc: Daisuke Nishimura
Cc: Balbir Singh
Reviewed-by: Minchan Kim
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
mem_cgroup_charge_common() is always called with @mem = NULL, so it's
meaningless. This patch removes it.Signed-off-by: Daisuke Nishimura
Cc: Balbir Singh
Acked-by: KAMEZAWA Hiroyuki
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
- try_get_mem_cgroup_from_mm() calls rcu_read_lock/unlock by itself, so we
don't have to call them in task_in_mem_cgroup().
- *mz is not used in __mem_cgroup_uncharge_common().
- we don't have to call lookup_page_cgroup() in mem_cgroup_end_migration()
after we've cleared PCG_MIGRATION of @oldpage.
- remove empty comment.
- remove redundant empty line in mem_cgroup_cache_charge().Signed-off-by: Daisuke Nishimura
Acked-by: Balbir Singh
Acked-by: KAMEZAWA Hiroyuki
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
Now, for checking a memcg is under task-account-moving, we do css_tryget()
against mc.to and mc.from. But this is just complicating things. This
patch makes the check easier.This patch adds a spinlock to move_charge_struct and guard modification of
mc.to and mc.from. By this, we don't have to think about complicated
races arount this not-critical path.[balbir@linux.vnet.ibm.com: don't crash on a null memcg being passed]
Signed-off-by: KAMEZAWA Hiroyuki
Signed-off-by: Balbir Singh
Cc: Daisuke Nishimura
Cc: Balbir Singh
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
mem_cgroup_try_charge() has a big loop in it and seems to be hard to read.
Most of routines are for slow path. This patch moves codes out from the
loop and make it clear what's done.Summary:
- refactoring a function to detect a memcg is under acccount move or not.
- refactoring a function to wait for the end of moving task acct.
- refactoring a main loop('s slow path) as a function and make it clear
why we retry or quit by return code.
- add fatal_signal_pending() check for bypassing charge loops.Signed-off-by: KAMEZAWA Hiroyuki
Cc: Daisuke Nishimura
Cc: Balbir Singh
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
This patch fixes possible deadlock in hugepage lock_page()
by adding missing unlock_page().libhugetlbfs test will hit this bug when the next patch in this
patchset ("hugetlb, HWPOISON: move PG_HWPoison bit check") is applied.Signed-off-by: Naoya Horiguchi
Signed-off-by: Jun'ichi Nomura
Acked-by: Fengguang Wu
Signed-off-by: Andi Kleen -
CONFIG_HUGETLBFS controls hugetlbfs interface code.
OTOH, CONFIG_HUGETLB_PAGE controls hugepage management code.
So we should use CONFIG_HUGETLB_PAGE here.Signed-off-by: Naoya Horiguchi
Signed-off-by: Andi Kleen -
This patch enables hwpoison injection through debug/hwpoison interfaces,
with which we can test memory error handling for free or reserved
hugepages (which cannot be tested by madvise() injector).[AK: Export PageHuge too for the injection module]
Signed-off-by: Naoya Horiguchi
Cc: Andrew Morton
Acked-by: Fengguang Wu
Signed-off-by: Andi Kleen -
This patch enables to block access to hwpoisoned hugepage and
also enables to block unmapping for it.Dependency:
"HWPOISON, hugetlb: enable error handling path for hugepage"Signed-off-by: Naoya Horiguchi
Cc: Andrew Morton
Acked-by: Fengguang Wu
Acked-by: Mel Gorman
Signed-off-by: Andi Kleen -
If error hugepage is not in-use, we can fully recovery from error
by dequeuing it from freelist, so return RECOVERY.
Otherwise whether or not we can recovery depends on user processes,
so return DELAYED.Dependency:
"HWPOISON, hugetlb: enable error handling path for hugepage"Signed-off-by: Naoya Horiguchi
Cc: Andrew Morton
Acked-by: Fengguang Wu
Signed-off-by: Andi Kleen -
For now all pages in the error hugepage are considered as hwpoisoned,
so count all of them in mce_bad_pages.Dependency:
"HWPOISON, hugetlb: enable error handling path for hugepage"Signed-off-by: Naoya Horiguchi
Cc: Andrew Morton
Acked-by: Fengguang Wu
Signed-off-by: Andi Kleen -
To avoid race condition between concurrent memory errors on identified
hugepage, we atomically test and set PG_hwpoison bit on the head page.
All pages in the error hugepage are considered as hwpoisoned
for now, so set and clear all PG_hwpoison bits in the hugepage
with page lock of the head page held.Dependency:
"HWPOISON, hugetlb: enable error handling path for hugepage"Signed-off-by: Naoya Horiguchi
Cc: Andrew Morton
Acked-by: Fengguang Wu
Signed-off-by: Andi Kleen -
This patch just enables handling path. Real containing and
recovering operation will be implemented in following patches.Dependency:
"hugetlb, rmap: add reverse mapping for hugepage."Signed-off-by: Naoya Horiguchi
Cc: Andi Kleen
Cc: Andrew Morton
Acked-by: Fengguang Wu
Signed-off-by: Andi Kleen -
This patch adds reverse mapping feature for hugepage by introducing
mapcount for shared/private-mapped hugepage and anon_vma for
private-mapped hugepage.While hugepage is not currently swappable, reverse mapping can be useful
for memory error handler.Without this patch, memory error handler cannot identify processes
using the bad hugepage nor unmap it from them. That is:
- for shared hugepage:
we can collect processes using a hugepage through pagecache,
but can not unmap the hugepage because of the lack of mapcount.
- for privately mapped hugepage:
we can neither collect processes nor unmap the hugepage.
This patch solves these problems.This patch include the bug fix given by commit 23be7468e8, so reverts it.
Dependency:
"hugetlb: move definition of is_vm_hugetlb_page() to hugepage_inline.h"ChangeLog since May 24.
- create hugetlb_inline.h and move is_vm_hugetlb_index() in it.
- move functions setting up anon_vma for hugepage into mm/rmap.c.ChangeLog since May 13.
- rebased to 2.6.34
- fix logic error (in case that private mapping and shared mapping coexist)
- move is_vm_hugetlb_page() into include/linux/mm.h to use this function
from linear_page_index()
- define and use linear_hugepage_index() instead of compound_order()
- use page_move_anon_rmap() in hugetlb_cow()
- copy exclusive switch of __set_page_anon_rmap() into hugepage counterpart.
- revert commit 24be7468 completelySigned-off-by: Naoya Horiguchi
Cc: Andi Kleen
Cc: Andrew Morton
Cc: Mel Gorman
Cc: Andrea Arcangeli
Cc: Larry Woodman
Cc: Lee Schermerhorn
Acked-by: Fengguang Wu
Acked-by: Mel Gorman
Signed-off-by: Andi Kleen -
* 'for-2.6.36' of git://git.kernel.dk/linux-2.6-block: (149 commits)
block: make sure that REQ_* types are seen even with CONFIG_BLOCK=n
xen-blkfront: fix missing out label
blkdev: fix blkdev_issue_zeroout return value
block: update request stacking methods to support discards
block: fix missing export of blk_types.h
writeback: fix bad _bh spinlock nesting
drbd: revert "delay probes", feature is being re-implemented differently
drbd: Initialize all members of sync_conf to their defaults [Bugz 315]
drbd: Disable delay probes for the upcomming release
writeback: cleanup bdi_register
writeback: add new tracepoints
writeback: remove unnecessary init_timer call
writeback: optimize periodic bdi thread wakeups
writeback: prevent unnecessary bdi threads wakeups
writeback: move bdi threads exiting logic to the forker thread
writeback: restructure bdi forker loop a little
writeback: move last_active to bdi
writeback: do not remove bdi from bdi_list
writeback: simplify bdi code a little
writeback: do not lose wake-ups in bdi threads
...Fixed up pretty trivial conflicts in drivers/block/virtio_blk.c and
drivers/scsi/scsi_error.c as per Jens. -
* 'kmemleak' of git://git.kernel.org/pub/scm/linux/kernel/git/cmarinas/linux-2.6-cm:
kmemleak: Fix typo in the comment
lib/scatterlist: Hook sg_kmalloc into kmemleak (v2)
kmemleak: Add DocBook style comments to kmemleak.c
kmemleak: Introduce a default off mode for kmemleak
kmemleak: Show more information for objects found by alias -
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs-2.6: (96 commits)
no need for list_for_each_entry_safe()/resetting with superblock list
Fix sget() race with failing mount
vfs: don't hold s_umount over close_bdev_exclusive() call
sysv: do not mark superblock dirty on remount
sysv: do not mark superblock dirty on mount
btrfs: remove junk sb_dirt change
BFS: clean up the superblock usage
AFFS: wait for sb synchronization when needed
AFFS: clean up dirty flag usage
cifs: truncate fallout
mbcache: fix shrinker function return value
mbcache: Remove unused features
add f_flags to struct statfs(64)
pass a struct path to vfs_statfs
update VFS documentation for method changes.
All filesystems that need invalidate_inode_buffers() are doing that explicitly
convert remaining ->clear_inode() to ->evict_inode()
Make ->drop_inode() just return whether inode needs to be dropped
fs/inode.c:clear_inode() is gone
fs/inode.c:evict() doesn't care about delete vs. non-delete paths now
...Fix up trivial conflicts in fs/nilfs2/super.c
10 Aug, 2010
5 commits
-
* 'merge' of git://git.kernel.org/pub/scm/linux/kernel/git/benh/powerpc:
powerpc: fix build with make 3.82
Revert "Input: appletouch - fix integer overflow issue"
memblock: Fix memblock_is_region_reserved() to return a boolean
powerpc: Trim defconfigs
powerpc: fix i8042 module build error
sound/soc: mpc5200_psc_ac97: Use gpio pins for cold reset
powerpc/5200: add mpc5200_psc_ac97_gpio_reset -
When taking a memory snapshot in hibernate_snapshot(), all (directly
called) memory allocations use GFP_ATOMIC. Hence swap misusage during
hibernation never occurs.But from a pessimistic point of view, there is no guarantee that no page
allcation has __GFP_WAIT. It is better to have a global indication "we
enter hibernation, don't use swap!".This patch tries to freeze new-swap-allocation during hibernation. (All
user processes are frozenm so swapin is not a concern).This way, no updates will happen to swap_map[] between
hibernate_snapshot() and save_image(). Swap is thawed when swsusp_free()
is called. We can be assured that swap corruption will not occur.Signed-off-by: KAMEZAWA Hiroyuki
Cc: "Rafael J. Wysocki"
Cc: Hugh Dickins
Cc: KOSAKI Motohiro
Cc: Ondrej Zary
Cc: Balbir Singh
Cc: Andrea Arcangeli
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
Since 2.6.31, swap_map[]'s refcounting was changed to show that a used
swap entry is just for swap-cache, can be reused. Then, while scanning
free entry in swap_map[], a swap entry may be able to be reclaimed and
reused. It was caused by commit c9e444103b5e7a5 ("mm: reuse unused swap
entry if necessary").But this caused deta corruption at resume. The scenario is
- Assume a clean-swap cache, but mapped.
- at hibernation_snapshot[], clean-swap-cache is saved as
clean-swap-cache and swap_map[] is marked as SWAP_HAS_CACHE.- then, save_image() is called. And reuse SWAP_HAS_CACHE entry to save
image, and break the contents.After resume:
- the memory reclaim runs and finds clean-not-referenced-swap-cache and
discards it because it's marked as clean. But here, the contents on
disk and swap-cache is inconsistent.Hance memory is corrupted.
This patch avoids the bug by not reclaiming swap-entry during hibernation.
This is a quick fix for backporting.Signed-off-by: KAMEZAWA Hiroyuki
Cc: Rafael J. Wysocki
Reported-by: Ondreg Zary
Tested-by: Ondreg Zary
Tested-by: Andrea Gelmini
Acked-by: Hugh Dickins
Cc:
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
Use compile-allocated memory instead of dynamic allocated memory for
mm_slots_hash.Use hash_ptr() instead divisions for bucket calculation.
Signed-off-by: Lai Jiangshan
Signed-off-by: Izik Eidus
Cc: Avi Kivity
Cc: Andrea Arcangeli
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
Fix "system goes unresponsive under memory pressure and lots of
dirty/writeback pages" bug.http://lkml.org/lkml/2010/4/4/86
In the above thread, Andreas Mohr described that
Invoking any command locked up for minutes (note that I'm
talking about attempted additional I/O to the _other_,
_unaffected_ main system HDD - such as loading some shell
binaries -, NOT the external SSD18M!!).This happens when the two conditions are both meet:
- under memory pressure
- writing heavily to a slow deviceOOM also happens in Andreas' system. The OOM trace shows that 3 processes
are stuck in wait_on_page_writeback() in the direct reclaim path. One in
do_fork() and the other two in unix_stream_sendmsg(). They are blocked on
this condition:(sc->order && priority < DEF_PRIORITY - 2)
which was introduced in commit 78dc583d (vmscan: low order lumpy reclaim
also should use PAGEOUT_IO_SYNC) one year ago. That condition may be too
permissive. In Andreas' case, 512MB/1024 = 512KB. If the direct reclaim
for the order-1 fork() allocation runs into a range of 512KB
hard-to-reclaim LRU pages, it will be stalled.It's a severe problem in three ways.
Firstly, it can easily happen in daily desktop usage. vmscan priority can
easily go below (DEF_PRIORITY - 2) on _local_ memory pressure. Even if
the system has 50% globally reclaimable pages, it still has good
opportunity to have 0.1% sized hard-to-reclaim ranges. For example, a
simple dd can easily create a big range (up to 20%) of dirty pages in the
LRU lists. And order-1 to order-3 allocations are more than common with
SLUB. Try "grep -v '1 :' /proc/slabinfo" to get the list of high order
slab caches. For example, the order-1 radix_tree_node slab cache may
stall applications at swap-in time; the order-3 inode cache on most
filesystems may stall applications when trying to read some file; the
order-2 proc_inode_cache may stall applications when trying to open a
/proc file.Secondly, once triggered, it will stall unrelated processes (not doing IO
at all) in the system. This "one slow USB device stalls the whole system"
avalanching effect is very bad.Thirdly, once stalled, the stall time could be intolerable long for the
users. When there are 20MB queued writeback pages and USB 1.1 is writing
them in 1MB/s, wait_on_page_writeback() will stuck for up to 20 seconds.
Not to mention it may be called multiple times.So raise the bar to only enable PAGEOUT_IO_SYNC when priority goes below
DEF_PRIORITY/3, or 6.25% LRU size. As the default dirty throttle ratio is
20%, it will hardly be triggered by pure dirty pages. We'd better treat
PAGEOUT_IO_SYNC as some last resort workaround -- its stall time is so
uncomfortably long (easily goes beyond 1s).The bar is only raised for (order < PAGE_ALLOC_COSTLY_ORDER) allocations,
which are easy to satisfy in 1TB memory boxes. So, although 6.25% of
memory could be an awful lot of pages to scan on a system with 1TB of
memory, it won't really have to busy scan that much.Andreas tested an older version of this patch and reported that it mostly
fixed his problem. Mel Gorman helped improve it and KOSAKI Motohiro will
fix it further in the next patch.Reported-by: Andreas Mohr
Reviewed-by: Minchan Kim
Reviewed-by: KOSAKI Motohiro
Signed-off-by: Mel Gorman
Signed-off-by: Wu Fengguang
Cc: Rik van Riel
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
