01 May, 2013
8 commits
-
cleancache_ops is used to decide whether backend is registered.
So now cleancache_enabled is always true if defined CONFIG_CLEANCACHE.Signed-off-by: Bob Liu
Cc: Wanpeng Li
Cc: Andor Daam
Cc: Dan Magenheimer
Cc: Florian Schmaus
Cc: Konrad Rzeszutek Wilk
Cc: Minchan Kim
Cc: Stefan Hengelein
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
Instead of using a backend_registered to determine whether a backend is
enabled. This allows us to remove the backend_register check and just
do 'if (cleancache_ops)'[v1: Rebase on top of b97c4b430b0a (ramster->zcache move]
Signed-off-by: Konrad Rzeszutek Wilk
Signed-off-by: Bob Liu
Cc: Wanpeng Li
Cc: Andor Daam
Cc: Dan Magenheimer
Cc: Florian Schmaus
Cc: Minchan Kim
Cc: Stefan Hengelein
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
With the goal of allowing tmem backends (zcache, ramster, Xen tmem) to
be built/loaded as modules rather than built-in and enabled by a boot
parameter, this patch provides "lazy initialization", allowing backends
to register to cleancache even after filesystems were mounted. Calls to
init_fs and init_shared_fs are remembered as fake poolids but no real
tmem_pools created. On backend registration the fake poolids are mapped
to real poolids and respective tmem_pools.Signed-off-by: Stefan Hengelein
Signed-off-by: Florian Schmaus
Signed-off-by: Andor Daam
Signed-off-by: Dan Magenheimer
[v1: Minor fixes: used #define for some values and bools]
[v2: Removed CLEANCACHE_HAS_LAZY_INIT]
[v3: Added more comments, added a lock for [shared_|]fs_poolid_map]
Signed-off-by: Konrad Rzeszutek Wilk
Signed-off-by: Bob Liu
Cc: Wanpeng Li
Cc: Minchan Kim
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
Frontswap initialization routine depends on swap_lock, which want to be
atomic about frontswap's first appearance. IOW, frontswap is not present
and will fail all calls OR frontswap is fully functional but if new
swap_info_struct isn't registered by enable_swap_info, swap subsystem
doesn't start I/O so there is no race between init procedure and page I/O
working on frontswap.So let's remove unnecessary swap_lock dependency.
Cc: Dan Magenheimer
Signed-off-by: Minchan Kim
[v1: Rebased on my branch, reworked to work with backends loading late]
[v2: Added a check for !map]
[v3: Made the invalidate path follow the init path]
[v4: Address comments by Wanpeng Li ]
Signed-off-by: Konrad Rzeszutek Wilk
Signed-off-by: Bob Liu
Cc: Wanpeng Li
Cc: Andor Daam
Cc: Florian Schmaus
Cc: Stefan Hengelein
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
After allowing tmem backends to build/run as modules, frontswap_enabled
always true if defined CONFIG_FRONTSWAP. But frontswap_test() depends on
whether backend is registered, mv it into frontswap.c using fronstswap_ops
to make the decision.frontswap_set/clear are not used outside frontswap, so don't export them.
Signed-off-by: Bob Liu
Cc: Wanpeng Li
Cc: Andor Daam
Cc: Dan Magenheimer
Cc: Florian Schmaus
Cc: Konrad Rzeszutek Wilk
Cc: Minchan Kim
Cc: Stefan Hengelein
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
This simplifies the code in the frontswap - we can get rid of the
'backend_registered' test and instead check against frontswap_ops.[v1: Rebase on top of 703ba7fe5e0 (ramster->zcache move]
Signed-off-by: Konrad Rzeszutek Wilk
Signed-off-by: Bob Liu
Cc: Wanpeng Li
Cc: Andor Daam
Cc: Dan Magenheimer
Cc: Florian Schmaus
Cc: Minchan Kim
Cc: Stefan Hengelein
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
With the goal of allowing tmem backends (zcache, ramster, Xen tmem) to
be built/loaded as modules rather than built-in and enabled by a boot
parameter, this patch provides "lazy initialization", allowing backends
to register to frontswap even after swapon was run. Before a backend
registers all calls to init are recorded and the creation of tmem_pools
delayed until a backend registers or until a frontswap store is
attempted.Signed-off-by: Stefan Hengelein
Signed-off-by: Florian Schmaus
Signed-off-by: Andor Daam
Signed-off-by: Dan Magenheimer
[v1: Fixes per Seth Jennings suggestions]
[v2: Removed FRONTSWAP_HAS_.. ]
[v3: Fix up per Bob Liu recommendations]
[v4: Fix up per Andrew's comments]
Signed-off-by: Konrad Rzeszutek Wilk
Signed-off-by: Bob Liu
Cc: Wanpeng Li
Cc: Dan Magenheimer
Cc: Minchan Kim
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
Pull trivial tree updates from Jiri Kosina:
"Usual stuff, mostly comment fixes, typo fixes, printk fixes and small
code cleanups"* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/trivial: (45 commits)
mm: Convert print_symbol to %pSR
gfs2: Convert print_symbol to %pSR
m32r: Convert print_symbol to %pSR
iostats.txt: add easy-to-find description for field 6
x86 cmpxchg.h: fix wrong comment
treewide: Fix typo in printk and comments
doc: devicetree: Fix various typos
docbook: fix 8250 naming in device-drivers
pata_pdc2027x: Fix compiler warning
treewide: Fix typo in printks
mei: Fix comments in drivers/misc/mei
treewide: Fix typos in kernel messages
pm44xx: Fix comment for "CONFIG_CPU_IDLE"
doc: Fix typo "CONFIG_CGROUP_CGROUP_MEMCG_SWAP"
mmzone: correct "pags" to "pages" in comment.
kernel-parameters: remove outdated 'noresidual' parameter
Remove spurious _H suffixes from ifdef comments
sound: Remove stray pluses from Kconfig file
radio-shark: Fix printk "CONFIG_LED_CLASS"
doc: put proper reference to CONFIG_MODULE_SIG_ENFORCE
...
30 Apr, 2013
32 commits
-
Merge second batch of fixes from Andrew Morton:
- various misc bits
- some printk updates
- a new "SRAM" driver.
- MAINTAINERS updates
- the backlight driver queue
- checkpatch updates
- a few init/ changes
- a huge number of drivers/rtc changes
- fatfs updates
- some lib/idr.c work
- some renaming of the random driver interfaces
* emailed patches from Andrew Morton : (285 commits)
net: rename random32 to prandom
net/core: remove duplicate statements by do-while loop
net/core: rename random32() to prandom_u32()
net/netfilter: rename random32() to prandom_u32()
net/sched: rename random32() to prandom_u32()
net/sunrpc: rename random32() to prandom_u32()
scsi: rename random32() to prandom_u32()
lguest: rename random32() to prandom_u32()
uwb: rename random32() to prandom_u32()
video/uvesafb: rename random32() to prandom_u32()
mmc: rename random32() to prandom_u32()
drbd: rename random32() to prandom_u32()
kernel/: rename random32() to prandom_u32()
mm/: rename random32() to prandom_u32()
lib/: rename random32() to prandom_u32()
x86: rename random32() to prandom_u32()
x86: pageattr-test: remove srandom32 call
uuid: use prandom_bytes()
raid6test: use prandom_bytes()
sctp: convert sctp_assoc_set_id() to use idr_alloc_cyclic()
... -
Pull cgroup updates from Tejun Heo:
- Fixes and a lot of cleanups. Locking cleanup is finally complete.
cgroup_mutex is no longer exposed to individual controlelrs which
used to cause nasty deadlock issues. Li fixed and cleaned up quite a
bit including long standing ones like racy cgroup_path().- device cgroup now supports proper hierarchy thanks to Aristeu.
- perf_event cgroup now supports proper hierarchy.
- A new mount option "__DEVEL__sane_behavior" is added. As indicated
by the name, this option is to be used for development only at this
point and generates a warning message when used. Unfortunately,
cgroup interface currently has too many brekages and inconsistencies
to implement a consistent and unified hierarchy on top. The new flag
is used to collect the behavior changes which are necessary to
implement consistent unified hierarchy. It's likely that this flag
won't be used verbatim when it becomes ready but will be enabled
implicitly along with unified hierarchy.The option currently disables some of broken behaviors in cgroup core
and also .use_hierarchy switch in memcg (will be routed through -mm),
which can be used to make very unusual hierarchy where nesting is
partially honored. It will also be used to implement hierarchy
support for blk-throttle which would be impossible otherwise without
introducing a full separate set of control knobs.This is essentially versioning of interface which isn't very nice but
at this point I can't see any other options which would allow keeping
the interface the same while moving towards hierarchy behavior which
is at least somewhat sane. The planned unified hierarchy is likely
to require some level of adaptation from userland anyway, so I think
it'd be best to take the chance and update the interface such that
it's supportable in the long term.Maintaining the existing interface does complicate cgroup core but
shouldn't put too much strain on individual controllers and I think
it'd be manageable for the foreseeable future. Maybe we'll be able
to drop it in a decade.Fix up conflicts (including a semantic one adding a new #include to ppc
that was uncovered by header the file changes) as per Tejun.* 'for-3.10' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup: (45 commits)
cpuset: fix compile warning when CONFIG_SMP=n
cpuset: fix cpu hotplug vs rebuild_sched_domains() race
cpuset: use rebuild_sched_domains() in cpuset_hotplug_workfn()
cgroup: restore the call to eventfd->poll()
cgroup: fix use-after-free when umounting cgroupfs
cgroup: fix broken file xattrs
devcg: remove parent_cgroup.
memcg: force use_hierarchy if sane_behavior
cgroup: remove cgrp->top_cgroup
cgroup: introduce sane_behavior mount option
move cgroupfs_root to include/linux/cgroup.h
cgroup: convert cgroupfs_root flag bits to masks and add CGRP_ prefix
cgroup: make cgroup_path() not print double slashes
Revert "cgroup: remove bind() method from cgroup_subsys."
perf: make perf_event cgroup hierarchical
cgroup: implement cgroup_is_descendant()
cgroup: make sure parent won't be destroyed before its children
cgroup: remove bind() method from cgroup_subsys.
devcg: remove broken_hierarchy tag
cgroup: remove cgroup_lock_is_held()
... -
Use preferable function name which implies using a pseudo-random
number generator.Signed-off-by: Akinobu Mita
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
The memcg is not referenced, so it can be destroyed at anytime right
after we exit rcu read section, so it's not safe to access it.To fix this, we call css_tryget() to get a reference while we're still
in rcu read section.This also removes a bogus comment above __memcg_create_cache_enqueue().
Signed-off-by: Li Zefan
Acked-by: Glauber Costa
Acked-by: Michal Hocko
Acked-by: KAMEZAWA Hiroyuki
Cc: Johannes Weiner
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
There are times when HIGHMEM is enabled, but we don't prefer
CONFIG_BOUNCE to be enabled. CONFIG_BOUNCE can reduce the block device
throughput, and this is not ideal for machines where we don't gain much
by enabling it. So provide an option to deselect CONFIG_BOUNCE. The
observation was made while measuring eMMC throughput using iozone on an
ARM device with 1GB RAM.Signed-off-by: Vinayak Menon
Cc: David Rientjes
Cc: Jens Axboe
Cc: Randy Dunlap
Cc: Russell King
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
Currently, we do memset() before reserving the area. This may not cause
any problem, but it is somewhat weird. So change execution order.Signed-off-by: Joonsoo Kim
Cc: Yinghai Lu
Acked-by: Johannes Weiner
Cc: Jiang Liu
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
Remove unused argument and make function static, because there is no user
outside of nobootmem.cSigned-off-by: Joonsoo Kim
Cc: Yinghai Lu
Acked-by: Johannes Weiner
Cc: Jiang Liu
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
PFN_PHYS() is a phys_addr_t, which can be u32 or u64.
Fix the build warning when phys_addr_t is u32.mm/memory_hotplug.c: warning: format '%llx' expects argument of type 'long long unsigned int', but argument 2 has type 'unsigned int' [-Wformat]: => 1685:3
mm/memory_hotplug.c: warning: format '%llx' expects argument of type 'long long unsigned int', but argument 3 has type 'unsigned int' [-Wformat]: => 1685:3Signed-off-by: Randy Dunlap
Reported-by: Geert Uytterhoeven
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
As pointed out by Andrew Morton, the swap-over-NFS writeback is not
setting PageWriteback before it is queued for direct IO. While swap
pages do not participate in BDI or process dirty accounting and the IO
is synchronous, the writeback bit is still required and not setting it
in this case was an oversight. swapoff depends on the page writeback to
synchronoise all pending writes on a swap page before it is reused.
Swapcache freeing and reuse depend on checking the PageWriteback under
lock to ensure the page is safe to reuse.Direct IO handlers and the direct IO handler for NFS do not deal with
PageWriteback as they are synchronous writes. In the case of NFS, it
schedules pages (or a page in the case of swap) for IO and then waits
synchronously for IO to complete in nfs_direct_write(). It is
recognised that this is a slowdown from normal swap handling which is
asynchronous and uses a completion handler. Shoving PageWriteback
handling down into direct IO handlers looks like a bad fit to handle the
swap case although it may have to be dealt with some day if swap is
converted to use direct IO in general and bmap is finally done away
with. At that point it will be necessary to refit asynchronous direct
IO with completion handlers onto the swap subsystem.As swapcache currently depends on PageWriteback to protect against
races, this patch sets PageWriteback under the page lock before queueing
it for direct IO. It is cleared when the direct IO handler returns. IO
errors are treated similarly to the direct-to-bio case except PageError
is not set as in the case of swap-over-NFS, it is likely to be a
transient error.It was asked what prevents such a page being reclaimed in parallel.
With this patch applied, such a page will now be skipped (most of the
time) or blocked until the writeback completes. Reclaim checks
PageWriteback under the page lock before calling try_to_free_swap and
the page lock should prevent the page being requeued for IO before it is
freed.This and Jerome's related patch should considered for -stable as far
back as 3.6 when swap-over-NFS was introduced.[akpm@linux-foundation.org: use pr_err_ratelimited()]
[akpm@linux-foundation.org: remove hopefully-unneeded cast in printk]
Signed-off-by: Mel Gorman
Cc: Jerome Marchand
Cc: Hugh Dickins
Cc: [3.6+]
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
Since commit 62c230bc1790 ("mm: add support for a filesystem to activate
swap files and use direct_IO for writing swap pages"), swap_writepage()
calls direct_IO on swap files. However, in that case the page isn't
redirtied if I/O fails, and is therefore handled afterwards as if it has
been successfully written to the swap file, leading to memory corruption
when the page is eventually swapped back in.This patch sets the page dirty when direct_IO() fails. It fixes a
memory corruption that happened while using swap-over-NFS.Signed-off-by: Jerome Marchand
Acked-by: Johannes Weiner
Acked-by: Mel Gorman
Cc: Hugh Dickins
Cc: [3.6+]
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
A memcg may livelock when oom if the process that grabs the hierarchy's
oom lock is never the first process with PF_EXITING set in the memcg's
task iteration.The oom killer, both global and memcg, will defer if it finds an
eligible process that is in the process of exiting and it is not being
ptraced. The idea is to allow it to exit without using memory reserves
before needlessly killing another process.This normally works fine except in the memcg case with a large number of
threads attached to the oom memcg. In this case, the memcg oom killer
only gets called for the process that grabs the hierarchy's oom lock;
all others end up blocked on the memcg's oom waitqueue. Thus, if the
process that grabs the hierarchy's oom lock is never the first
PF_EXITING process in the memcg's task iteration, the oom killer is
constantly deferred without anything making progress.The fix is to give PF_EXITING processes access to memory reserves so
that we've marked them as oom killed without any iteration. This allows
__mem_cgroup_try_charge() to succeed so that the process may exit. This
makes the memcg oom killer exemption for TIF_MEMDIE tasks, now
immediately granted for processes with pending SIGKILLs and those in the
exit path, to be equivalent to what is done for the global oom killer.Signed-off-by: David Rientjes
Acked-by: Michal Hocko
Acked-by: KAMEZAWA Hiroyuki
Acked-by: Johannes Weiner
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
Current implementation of huge zero page uses pfn value 0 to indicate
that the page hasn't allocated yet. It assumes that buddy page
allocator can't return page with pfn == 0.Let's rework the code to store 'struct page *' of huge zero page, not
its pfn. This way we can avoid the weak assumption.[akpm@linux-foundation.org: fix sparse warning]
Signed-off-by: Kirill A. Shutemov
Reported-by: Minchan Kim
Acked-by: Minchan Kim
Reviewed-by: Andrea Arcangeli
Acked-by: Johannes Weiner
Cc: Wu Fengguang
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
This might cause a use-after-free bug.
Signed-off-by: Li Zefan
Cc: Glauber Costa
Acked-by: Michal Hocko
Acked-by: KAMEZAWA Hiroyuki
Cc: Johannes Weiner
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
There are two convenient ways to report errors to userspace
1) retun error to original syscall for example write(2)
2) mark mapping with error flag and return it on later fsync(2)Second one is broken if (mapping->nrpages == 0) This is real-life
situation because after error pages are likey to be truncated or
invalidated.We have to return an error regardless to number of pages in the mapping.
#Original testcase: git@github.com:dmonakhov/xfstests.git
MOUNT_OPTIONS="-b1024"
./check shared/305Signed-off-by: Dmitry Monakhov
Reviewed-by: Jan Kara
Cc: Al Viro
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
There is no comment for parameter nid of memblock_insert_region().
This patch adds comment for it.Signed-off-by: Tang Chen
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
Signed-off-by: Cody P Schafer
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
In page reclaim, huge page is split. split_huge_page() adds tail pages
to LRU list. Since we are reclaiming a huge page, it's better we
reclaim all subpages of the huge page instead of just the head page.
This patch adds split tail pages to shrink page list so the tail pages
can be reclaimed soon.Before this patch, run a swap workload:
thp_fault_alloc 3492
thp_fault_fallback 608
thp_collapse_alloc 6
thp_collapse_alloc_failed 0
thp_split 916With this patch:
thp_fault_alloc 4085
thp_fault_fallback 16
thp_collapse_alloc 90
thp_collapse_alloc_failed 0
thp_split 1272fallback allocation is reduced a lot.
[akpm@linux-foundation.org: fix CONFIG_SWAP=n build]
Signed-off-by: Shaohua Li
Acked-by: Rik van Riel
Acked-by: Minchan Kim
Acked-by: Johannes Weiner
Reviewed-by: Wanpeng Li
Cc: Andrea Arcangeli
Cc: Hugh Dickins
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
To prevent flooding the swap device with writebacks, frontswap backends
need to count and limit the number of outstanding writebacks. The
incrementing of the counter can be done before the call to
__swap_writepage(). However, the caller must receive a notification
when the writeback completes in order to decrement the counter.To achieve this functionality, this patch modifies __swap_writepage() to
take the bio completion callback function as an argument.end_swap_bio_write(), the normal bio completion function, is also made
non-static so that code doing the accounting can call it after the
accounting is done.There should be no behavioural change to existing code.
Signed-off-by: Seth Jennings
Signed-off-by: Bob Liu
Acked-by: Minchan Kim
Reviewed-by: Dan Magenheimer
Cc: Konrad Rzeszutek Wilk
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
swap_writepage() is currently where frontswap hooks into the swap write
path to capture pages with the frontswap_store() function. However, if
a frontswap backend wants to "resume" the writeback of a page to the
swap device, it can't call swap_writepage() as the page will simply
reenter the backend.This patch separates swap_writepage() into a top and bottom half, the
bottom half named __swap_writepage() to allow a frontswap backend, like
zswap, to resume writeback beyond the frontswap_store() hook.__add_to_swap_cache() is also made non-static so that the page for which
writeback is to be resumed can be added to the swap cache.Signed-off-by: Seth Jennings
Signed-off-by: Bob Liu
Acked-by: Minchan Kim
Reviewed-by: Dan Magenheimer
Cc: Konrad Rzeszutek Wilk
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
Fix a corner case for MAP_FIXED when requested mapping length is larger
than rlimit for virtual memory. In such case any overlapping mappings
are unmapped before we check for the limit and return ENOMEM.The check is moved before the loop that unmaps overlapping parts of
existing mappings. When we are about to hit the limit (currently mapped
pages + len > limit) we scan for overlapping pages and check again
accounting for them.This fixes situation when userspace program expects that the previous
mappings are preserved after the mmap() syscall has returned with error.
(POSIX clearly states that successfull mapping shall replace any
previous mappings.)This corner case was found and can be tested with LTP testcase:
testcases/open_posix_testsuite/conformance/interfaces/mmap/24-2.c
In this case the mmap, which is clearly over current limit, unmaps
dynamic libraries and the testcase segfaults right after returning into
userspace.I've also looked at the second instance of the unmapping loop in the
do_brk(). The do_brk() is called from brk() syscall and from vm_brk().
The brk() syscall checks for overlapping mappings and bails out when
there are any (so it can't be triggered from the brk syscall). The
vm_brk() is called only from binmft handlers so it shouldn't be
triggered unless binmft handler created overlapping mappings.Signed-off-by: Cyril Hrubis
Reviewed-by: Mel Gorman
Reviewed-by: Wanpeng Li
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
With this patch userland applications that want to maintain the
interactivity/memory allocation cost can use the pressure level
notifications. The levels are defined like this:The "low" level means that the system is reclaiming memory for new
allocations. Monitoring this reclaiming activity might be useful for
maintaining cache level. Upon notification, the program (typically
"Activity Manager") might analyze vmstat and act in advance (i.e.
prematurely shutdown unimportant services).The "medium" level means that the system is experiencing medium memory
pressure, the system might be making swap, paging out active file
caches, etc. Upon this event applications may decide to further analyze
vmstat/zoneinfo/memcg or internal memory usage statistics and free any
resources that can be easily reconstructed or re-read from a disk.The "critical" level means that the system is actively thrashing, it is
about to out of memory (OOM) or even the in-kernel OOM killer is on its
way to trigger. Applications should do whatever they can to help the
system. It might be too late to consult with vmstat or any other
statistics, so it's advisable to take an immediate action.The events are propagated upward until the event is handled, i.e. the
events are not pass-through. Here is what this means: for example you
have three cgroups: A->B->C. Now you set up an event listener on
cgroups A, B and C, and suppose group C experiences some pressure. In
this situation, only group C will receive the notification, i.e. groups
A and B will not receive it. This is done to avoid excessive
"broadcasting" of messages, which disturbs the system and which is
especially bad if we are low on memory or thrashing. So, organize the
cgroups wisely, or propagate the events manually (or, ask us to
implement the pass-through events, explaining why would you need them.)Performance wise, the memory pressure notifications feature itself is
lightweight and does not require much of bookkeeping, in contrast to the
rest of memcg features. Unfortunately, as of current memcg
implementation, pages accounting is an inseparable part and cannot be
turned off. The good news is that there are some efforts[1] to improve
the situation; plus, implementing the same, fully API-compatible[2]
interface for CONFIG_MEMCG=n case (e.g. embedded) is also a viable
option, so it will not require any changes on the userland side.[1] http://permalink.gmane.org/gmane.linux.kernel.cgroups/6291
[2] http://lkml.org/lkml/2013/2/21/454[akpm@linux-foundation.org: coding-style fixes]
[akpm@linux-foundation.org: fix CONFIG_CGROPUPS=n warnings]
Signed-off-by: Anton Vorontsov
Acked-by: Kirill A. Shutemov
Acked-by: KAMEZAWA Hiroyuki
Cc: Tejun Heo
Cc: David Rientjes
Cc: Pekka Enberg
Cc: Mel Gorman
Cc: Glauber Costa
Cc: Michal Hocko
Cc: Luiz Capitulino
Cc: Greg Thelen
Cc: Leonid Moiseichuk
Cc: KOSAKI Motohiro
Cc: Minchan Kim
Cc: Bartlomiej Zolnierkiewicz
Cc: John Stultz
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
In madvise(), there doesn't seem to be any reason for taking the
¤t->mm->mmap_sem before start and len_in have been validated.
Incidentally, this removes the need for the out: label.[akpm@linux-foundation.org: s/out_plug/out/, per David]
Signed-off-by: Rasmus Villemoes
Acked-by: KOSAKI Motohiro
Acked-by: David Rientjes
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
__remove_pages() is only necessary for CONFIG_MEMORY_HOTREMOVE. PowerPC
pseries will return -EOPNOTSUPP if unsupported.Adding an #ifdef causes several other functions it depends on to also
become unnecessary, which saves in .text when disabled (it's disabled in
most defconfigs besides powerpc, including x86). remove_memory_block()
becomes static since it is not referenced outside of
drivers/base/memory.c.Build tested on x86 and powerpc with CONFIG_MEMORY_HOTREMOVE both enabled
and disabled.Signed-off-by: David Rientjes
Acked-by: Toshi Kani
Cc: Benjamin Herrenschmidt
Cc: Paul Mackerras
Cc: Greg Kroah-Hartman
Cc: Wen Congyang
Cc: Tang Chen
Cc: Yasuaki Ishimatsu
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
Change __remove_pages() to call release_mem_region_adjustable(). This
allows a requested memory range to be released from the iomem_resource
table even if it does not match exactly to an resource entry but still
fits into. The resource entries initialized at bootup usually cover the
whole contiguous memory ranges and may not necessarily match with the
size of memory hot-delete requests.If release_mem_region_adjustable() failed, __remove_pages() emits a
warning message and continues to proceed as it was the case with
release_mem_region(). release_mem_region(), which is defined to
__release_region(), emits a warning message and returns no error since a
void function.Signed-off-by: Toshi Kani
Reviewed-by : Yasuaki Ishimatsu
Acked-by: David Rientjes
Cc: Ram Pai
Cc: T Makphaibulchoke
Cc: Wen Congyang
Cc: Tang Chen
Cc: Jiang Liu
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
The comment over migrate_pages() looks quite weird, and makes it hard to
grasp what it is trying to say. Rewrite it more comprehensibly.Signed-off-by: Srivatsa S. Bhat
Acked-by: Christoph Lameter
Cc: Mel Gorman
Cc: Hugh Dickins
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
Currently the memory barrier in __do_huge_pmd_anonymous_page doesn't
work. Because lru_cache_add_lru uses pagevec so it could miss spinlock
easily so above rule was broken so user might see inconsistent data.I was not first person who pointed out the problem. Mel and Peter
pointed out a few months ago and Peter pointed out further that even
spin_lock/unlock can't make sure of it:http://marc.info/?t=134333512700004
In particular:
*A = a;
LOCK
UNLOCK
*B = b;may occur as:
LOCK, STORE *B, STORE *A, UNLOCK
At last, Hugh pointed out that even we don't need memory barrier in
there because __SetPageUpdate already have done it from Nick's commit
0ed361dec369 ("mm: fix PageUptodate data race") explicitly.So this patch fixes comment on THP and adds same comment for
do_anonymous_page, too because everybody except Hugh was missing that.
It means we need a comment about that.Signed-off-by: Minchan Kim
Acked-by: Andrea Arcangeli
Acked-by: David Rientjes
Acked-by: KAMEZAWA Hiroyuki
Cc: Mel Gorman
Cc: Hugh Dickins
Cc: Peter Zijlstra
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
CONFIG_HOTPLUG is going away as an option, cleanup CONFIG_HOTPLUG
ifdefs in mm files.Signed-off-by: Yijing Wang
Acked-by: Greg Kroah-Hartman
Acked-by: Rik van Riel
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
Just a trivial issue I stumbled on while doing something else...
Signed-off-by: Michel Lespinasse
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
Alter the admin and user reserves of the previous patches in this series
when memory is added or removed.If memory is added and the reserves have been eliminated or increased
above the default max, then we'll trust the admin.If memory is removed and there isn't enough free memory, then we need to
reset the reserves.Otherwise keep the reserve set by the admin.
The reserve reset code is the same as the reserve initialization code.
I tested hot addition and removal by triggering it via sysfs. The
reserves shrunk when they were set high and memory was removed. They
were reset higher when memory was added again.[akpm@linux-foundation.org: use register_hotmemory_notifier()]
[akpm@linux-foundation.org: init_user_reserve() and init_admin_reserve can no longer be __meminit]
[fengguang.wu@intel.com: make init_reserve_notifier() static]
[akpm@linux-foundation.org: coding-style fixes]
Signed-off-by: Andrew Shewmaker
Signed-off-by: Fengguang Wu
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
Add an admin_reserve_kbytes knob to allow admins to change the hardcoded
memory reserve to something other than 3%, which may be multiple
gigabytes on large memory systems. Only about 8MB is necessary to
enable recovery in the default mode, and only a few hundred MB are
required even when overcommit is disabled.This affects OVERCOMMIT_GUESS and OVERCOMMIT_NEVER.
admin_reserve_kbytes is initialized to min(3% free pages, 8MB)
I arrived at 8MB by summing the RSS of sshd or login, bash, and top.
Please see first patch in this series for full background, motivation,
testing, and full changelog.[akpm@linux-foundation.org: coding-style fixes]
[akpm@linux-foundation.org: make init_admin_reserve() static]
Signed-off-by: Andrew Shewmaker
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
Add user_reserve_kbytes knob.
Limit the growth of the memory reserved for other user processes to
min(3% current process size, user_reserve_pages). Only about 8MB is
necessary to enable recovery in the default mode, and only a few hundred
MB are required even when overcommit is disabled.user_reserve_pages defaults to min(3% free pages, 128MB)
I arrived at 128MB by taking the max VSZ of sshd, login, bash, and top ...
then adding the RSS of each.This only affects OVERCOMMIT_NEVER mode.
Background
1. user reserve
__vm_enough_memory reserves a hardcoded 3% of the current process size for
other applications when overcommit is disabled. This was done so that a
user could recover if they launched a memory hogging process. Without the
reserve, a user would easily run into a message such as:bash: fork: Cannot allocate memory
2. admin reserve
Additionally, a hardcoded 3% of free memory is reserved for root in both
overcommit 'guess' and 'never' modes. This was intended to prevent a
scenario where root-cant-log-in and perform recovery operations.Note that this reserve shrinks, and doesn't guarantee a useful reserve.
Motivation
The two hardcoded memory reserves should be updated to account for current
memory sizes.Also, the admin reserve would be more useful if it didn't shrink too much.
When the current code was originally written, 1GB was considered
"enterprise". Now the 3% reserve can grow to multiple GB on large memory
systems, and it only needs to be a few hundred MB at most to enable a user
or admin to recover a system with an unwanted memory hogging process.I've found that reducing these reserves is especially beneficial for a
specific type of application load:* single application system
* one or few processes (e.g. one per core)
* allocating all available memory
* not initializing every page immediately
* long runningI've run scientific clusters with this sort of load. A long running job
sometimes failed many hours (weeks of CPU time) into a calculation. They
weren't initializing all of their memory immediately, and they weren't
using calloc, so I put systems into overcommit 'never' mode. These
clusters run diskless and have no swap.However, with the current reserves, a user wishing to allocate as much
memory as possible to one process may be prevented from using, for
example, almost 2GB out of 32GB.The effect is less, but still significant when a user starts a job with
one process per core. I have repeatedly seen a set of processes
requesting the same amount of memory fail because one of them could not
allocate the amount of memory a user would expect to be able to allocate.
For example, Message Passing Interfce (MPI) processes, one per core. And
it is similar for other parallel programming frameworks.Changing this reserve code will make the overcommit never mode more useful
by allowing applications to allocate nearly all of the available memory.Also, the new admin_reserve_kbytes will be safer than the current behavior
since the hardcoded 3% of available memory reserve can shrink to something
useless in the case where applications have grabbed all available memory.Risks
* "bash: fork: Cannot allocate memory"
The downside of the first patch-- which creates a tunable user reserve
that is only used in overcommit 'never' mode--is that an admin can set
it so low that a user may not be able to kill their process, even if
they already have a shell prompt.Of course, a user can get in the same predicament with the current 3%
reserve--they just have to launch processes until 3% becomes negligible.* root-cant-log-in problem
The second patch, adding the tunable rootuser_reserve_pages, allows
the admin to shoot themselves in the foot by setting it too small. They
can easily get the system into a state where root-can't-log-in.However, the new admin_reserve_kbytes will be safer than the current
behavior since the hardcoded 3% of available memory reserve can shrink
to something useless in the case where applications have grabbed all
available memory.Alternatives
* Memory cgroups provide a more flexible way to limit application memory.
Not everyone wants to set up cgroups or deal with their overhead.
* We could create a fourth overcommit mode which provides smaller reserves.
The size of useful reserves may be drastically different depending
on the whether the system is embedded or enterprise.* Force users to initialize all of their memory or use calloc.
Some users don't want/expect the system to overcommit when they malloc.
Overcommit 'never' mode is for this scenario, and it should work well.The new user and admin reserve tunables are simple to use, with low
overhead compared to cgroups. The patches preserve current behavior where
3% of memory is less than 128MB, except that the admin reserve doesn't
shrink to an unusable size under pressure. The code allows admins to tune
for embedded and enterprise usage.FAQ
* How is the root-cant-login problem addressed?
What happens if admin_reserve_pages is set to 0?Root is free to shoot themselves in the foot by setting
admin_reserve_kbytes too low.On x86_64, the minimum useful reserve is:
8MB for overcommit 'guess'
128MB for overcommit 'never'admin_reserve_pages defaults to min(3% free memory, 8MB)
So, anyone switching to 'never' mode needs to adjust
admin_reserve_pages.* How do you calculate a minimum useful reserve?
A user or the admin needs enough memory to login and perform
recovery operations, which includes, at a minimum:sshd or login + bash (or some other shell) + top (or ps, kill, etc.)
For overcommit 'guess', we can sum resident set sizes (RSS)
because we only need enough memory to handle what the recovery
programs will typically use. On x86_64 this is about 8MB.For overcommit 'never', we can take the max of their virtual sizes (VSZ)
and add the sum of their RSS. We use VSZ instead of RSS because mode
forces us to ensure we can fulfill all of the requested memory allocations--
even if the programs only use a fraction of what they ask for.
On x86_64 this is about 128MB.When swap is enabled, reserves are useful even when they are as
small as 10MB, regardless of overcommit mode.When both swap and overcommit are disabled, then the admin should
tune the reserves higher to be absolutley safe. Over 230MB each
was safest in my testing.* What happens if user_reserve_pages is set to 0?
Note, this only affects overcomitt 'never' mode.
Then a user will be able to allocate all available memory minus
admin_reserve_kbytes.However, they will easily see a message such as:
"bash: fork: Cannot allocate memory"
And they won't be able to recover/kill their application.
The admin should be able to recover the system if
admin_reserve_kbytes is set appropriately.* What's the difference between overcommit 'guess' and 'never'?
"Guess" allows an allocation if there are enough free + reclaimable
pages. It has a hardcoded 3% of free pages reserved for root."Never" allows an allocation if there is enough swap + a configurable
percentage (default is 50) of physical RAM. It has a hardcoded 3% of
free pages reserved for root, like "Guess" mode. It also has a
hardcoded 3% of the current process size reserved for additional
applications.* Why is overcommit 'guess' not suitable even when an app eventually
writes to every page? It takes free pages, file pages, available
swap pages, reclaimable slab pages into consideration. In other words,
these are all pages available, then why isn't overcommit suitable?Because it only looks at the present state of the system. It
does not take into account the memory that other applications have
malloced, but haven't initialized yet. It overcommits the system.Test Summary
There was little change in behavior in the default overcommit 'guess'
mode with swap enabled before and after the patch. This was expected.Systems run most predictably (i.e. no oom kills) in overcommit 'never'
mode with swap enabled. This also allowed the most memory to be allocated
to a user application.Overcommit 'guess' mode without swap is a bad idea. It is easy to
crash the system. None of the other tested combinations crashed.
This matches my experience on the Roadrunner supercomputer.Without the tunable user reserve, a system in overcommit 'never' mode
and without swap does not allow the admin to recover, although the
admin can.With the new tunable reserves, a system in overcommit 'never' mode
and without swap can be configured to:1. maximize user-allocatable memory, running close to the edge of
recoverability2. maximize recoverability, sacrificing allocatable memory to
ensure that a user cannot take down a systemTest Description
Fedora 18 VM - 4 x86_64 cores, 5725MB RAM, 4GB Swap
System is booted into multiuser console mode, with unnecessary services
turned off. Caches were dropped before each test.Hogs are user memtester processes that attempt to allocate all free memory
as reported by /proc/meminfoIn overcommit 'never' mode, memory_ratio=100
Test Results
3.9.0-rc1-mm1
Overcommit | Swap | Hogs | MB Got/Wanted | OOMs | User Recovery | Admin Recovery
---------- ---- ---- ------------- ---- ------------- --------------
guess yes 1 5432/5432 no yes yes
guess yes 4 5444/5444 1 yes yes
guess no 1 5302/5449 no yes yes
guess no 4 - crash no nonever yes 1 5460/5460 1 yes yes
never yes 4 5460/5460 1 yes yes
never no 1 5218/5432 no no yes
never no 4 5203/5448 no no yes3.9.0-rc1-mm1-tunablereserves
User and Admin Recovery show their respective reserves, if applicable.
Overcommit | Swap | Hogs | MB Got/Wanted | OOMs | User Recovery | Admin Recovery
---------- ---- ---- ------------- ---- ------------- --------------
guess yes 1 5419/5419 no - yes 8MB yes
guess yes 4 5436/5436 1 - yes 8MB yes
guess no 1 5440/5440 * - yes 8MB yes
guess no 4 - crash - no 8MB no* process would successfully mlock, then the oom killer would pick it
never yes 1 5446/5446 no 10MB yes 20MB yes
never yes 4 5456/5456 no 10MB yes 20MB yes
never no 1 5387/5429 no 128MB no 8MB barely
never no 1 5323/5428 no 226MB barely 8MB barely
never no 1 5323/5428 no 226MB barely 8MB barelynever no 1 5359/5448 no 10MB no 10MB barely
never no 1 5323/5428 no 0MB no 10MB barely
never no 1 5332/5428 no 0MB no 50MB yes
never no 1 5293/5429 no 0MB no 90MB yesnever no 1 5001/5427 no 230MB yes 338MB yes
never no 4* 4998/5424 no 230MB yes 338MB yes* more memtesters were launched, able to allocate approximately another 100MB
Future Work
- Test larger memory systems.
- Test an embedded image.
- Test other architectures.
- Time malloc microbenchmarks.
- Would it be useful to be able to set overcommit policy for
each memory cgroup?- Some lines are slightly above 80 chars.
Perhaps define a macro to convert between pages and kb?
Other places in the kernel do this.[akpm@linux-foundation.org: coding-style fixes]
[akpm@linux-foundation.org: make init_user_reserve() static]
Signed-off-by: Andrew Shewmaker
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
Squishes a statement-with-no-effect warning, removes some ifdefs and
shrinks .text by 2 bytes.Note that this code fails to check for blocking_notifier_chain_register()
failures.Cc: Pekka Enberg
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
