29 Mar, 2012
10 commits
-
Merge third batch of patches from Andrew Morton:
- Some MM stragglers
- core SMP library cleanups (on_each_cpu_mask)
- Some IPI optimisations
- kexec
- kdump
- IPMI
- the radix-tree iterator work
- various other misc bits."That'll do for -rc1. I still have ~10 patches for 3.4, will send
those along when they've baked a little more."* emailed from Andrew Morton : (35 commits)
backlight: fix typo in tosa_lcd.c
crc32: add help text for the algorithm select option
mm: move hugepage test examples to tools/testing/selftests/vm
mm: move slabinfo.c to tools/vm
mm: move page-types.c from Documentation to tools/vm
selftests/Makefile: make `run_tests' depend on `all'
selftests: launch individual selftests from the main Makefile
radix-tree: use iterators in find_get_pages* functions
radix-tree: rewrite gang lookup using iterator
radix-tree: introduce bit-optimized iterator
fs/proc/namespaces.c: prevent crash when ns_entries[] is empty
nbd: rename the nbd_device variable from lo to nbd
pidns: add reboot_pid_ns() to handle the reboot syscall
sysctl: use bitmap library functions
ipmi: use locks on watchdog timeout set on reboot
ipmi: simplify locking
ipmi: fix message handling during panics
ipmi: use a tasklet for handling received messages
ipmi: increase KCS timeouts
ipmi: decrease the IPMI message transaction time in interrupt mode
... -
Replace radix_tree_gang_lookup_slot() and
radix_tree_gang_lookup_tag_slot() in page-cache lookup functions with
brand-new radix-tree direct iterating. This avoids the double-scanning
and pointer copying.Iterator don't stop after nr_pages page-get fails in a row, it continue
lookup till the radix-tree end. Thus we can safely remove these restart
conditions.Unfortunately, old implementation didn't forbid nr_pages == 0, this corner
case does not fit into new code, so the patch adds an extra check at the
beginning.Signed-off-by: Konstantin Khlebnikov
Tested-by: Hugh Dickins
Cc: Christoph Hellwig
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
Calculate a cpumask of CPUs with per-cpu pages in any zone and only send
an IPI requesting CPUs to drain these pages to the buddy allocator if they
actually have pages when asked to flush.This patch saves 85%+ of IPIs asking to drain per-cpu pages in case of
severe memory pressure that leads to OOM since in these cases multiple,
possibly concurrent, allocation requests end up in the direct reclaim code
path so when the per-cpu pages end up reclaimed on first allocation
failure for most of the proceeding allocation attempts until the memory
pressure is off (possibly via the OOM killer) there are no per-cpu pages
on most CPUs (and there can easily be hundreds of them).This also has the side effect of shortening the average latency of direct
reclaim by 1 or more order of magnitude since waiting for all the CPUs to
ACK the IPI takes a long time.Tested by running "hackbench 400" on a 8 CPU x86 VM and observing the
difference between the number of direct reclaim attempts that end up in
drain_all_pages() and those were more then 1/2 of the online CPU had any
per-cpu page in them, using the vmstat counters introduced in the next
patch in the series and using proc/interrupts.In the test sceanrio, this was seen to save around 3600 global
IPIs after trigerring an OOM on a concurrent workload:$ cat /proc/vmstat | tail -n 2
pcp_global_drain 0
pcp_global_ipi_saved 0$ cat /proc/interrupts | grep CAL
CAL: 1 2 1 2
2 2 2 2 Function call interrupts$ hackbench 400
[OOM messages snipped]$ cat /proc/vmstat | tail -n 2
pcp_global_drain 3647
pcp_global_ipi_saved 3642$ cat /proc/interrupts | grep CAL
CAL: 6 13 6 3
3 3 1 2 7 Function call interruptsPlease note that if the global drain is removed from the direct reclaim
path as a patch from Mel Gorman currently suggests this should be replaced
with an on_each_cpu_cond invocation.Signed-off-by: Gilad Ben-Yossef
Acked-by: Mel Gorman
Cc: KOSAKI Motohiro
Acked-by: Christoph Lameter
Acked-by: Peter Zijlstra
Cc: Pekka Enberg
Cc: Rik van Riel
Cc: Andi Kleen
Acked-by: Michal Nazarewicz
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
flush_all() is called for each kmem_cache_destroy(). So every cache being
destroyed dynamically ends up sending an IPI to each CPU in the system,
regardless if the cache has ever been used there.For example, if you close the Infinband ipath driver char device file, the
close file ops calls kmem_cache_destroy(). So running some infiniband
config tool on one a single CPU dedicated to system tasks might interrupt
the rest of the 127 CPUs dedicated to some CPU intensive or latency
sensitive task.I suspect there is a good chance that every line in the output of "git
grep kmem_cache_destroy linux/ | grep '\->'" has a similar scenario.This patch attempts to rectify this issue by sending an IPI to flush the
per cpu objects back to the free lists only to CPUs that seem to have such
objects.The check which CPU to IPI is racy but we don't care since asking a CPU
without per cpu objects to flush does no damage and as far as I can tell
the flush_all by itself is racy against allocs on remote CPUs anyway, so
if you required the flush_all to be determinstic, you had to arrange for
locking regardless.Without this patch the following artificial test case:
$ cd /sys/kernel/slab
$ for DIR in *; do cat $DIR/alloc_calls > /dev/null; doneproduces 166 IPIs on an cpuset isolated CPU. With it it produces none.
The code path of memory allocation failure for CPUMASK_OFFSTACK=y
config was tested using fault injection framework.Signed-off-by: Gilad Ben-Yossef
Acked-by: Christoph Lameter
Cc: Chris Metcalf
Acked-by: Peter Zijlstra
Cc: Frederic Weisbecker
Cc: Russell King
Cc: Pekka Enberg
Cc: Matt Mackall
Cc: Sasha Levin
Cc: Rik van Riel
Cc: Andi Kleen
Cc: Mel Gorman
Cc: Alexander Viro
Cc: Avi Kivity
Cc: Michal Nazarewicz
Cc: Kosaki Motohiro
Cc: Milton Miller
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
Most system calls taking flags first check that the flags passed in are
valid, and that helps userspace to detect when new flags are supported.But swapon never did so: start checking now, to help if we ever want to
support more swap_flags in future.It's difficult to get stray bits set in an int, and swapon is not widely
used, so this is most unlikely to break any userspace; but we can just
revert if it turns out to do so.Signed-off-by: Hugh Dickins
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
The size of coredump files is limited by RLIMIT_CORE, however, allocating
large amounts of memory results in three negative consequences:- the coredumping process may be chosen for oom kill and quickly deplete
all memory reserves in oom conditions preventing further progress from
being made or tasks from exiting,- the coredumping process may cause other processes to be oom killed
without fault of their own as the result of a SIGSEGV, for example, in
the coredumping process, or- the coredumping process may result in a livelock while writing to the
dump file if it needs memory to allocate while other threads are in
the exit path waiting on the coredumper to complete.This is fixed by implying __GFP_NORETRY in the page allocator for
coredumping processes when reclaim has failed so the allocations fail and
the process continues to exit.Signed-off-by: David Rientjes
Cc: Mel Gorman
Cc: KAMEZAWA Hiroyuki
Cc: Minchan Kim
Cc: Oleg Nesterov
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
pmd_trans_unstable() should be called before pmd_offset_map() in the
locations where the mmap_sem is held for reading.Signed-off-by: Andrea Arcangeli
Cc: Mel Gorman
Cc: Hugh Dickins
Cc: Larry Woodman
Cc: Ulrich Obergfell
Cc: Rik van Riel
Cc: Mark Salter
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
Holepunching filesystems ext4 and xfs are using truncate_inode_pages_range
but forgetting to unmap pages first (ocfs2 remembers). This is not really
a bug, since races already require truncate_inode_page() to handle that
case once the page is locked; but it can be very inefficient if the file
being punched happens to be mapped into many vmas.Provide a drop-in replacement truncate_pagecache_range() which does the
unmapping pass first, handling the awkward mismatch between arguments to
truncate_inode_pages_range() and arguments to unmap_mapping_range().Note that holepunching does not unmap privately COWed pages in the range:
POSIX requires that we do so when truncating, but it's hard to justify,
difficult to implement without an i_size cutoff, and no filesystem is
attempting to implement it.Signed-off-by: Hugh Dickins
Cc: "Theodore Ts'o"
Cc: Andreas Dilger
Cc: Mark Fasheh
Cc: Joel Becker
Cc: Ben Myers
Cc: Alex Elder
Cc: Christoph Hellwig
Cc: Dave Chinner
Cc: Al Viro
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
Pull SLAB changes from Pekka Enberg:
"There's the new kmalloc_array() API, minor fixes and performance
improvements, but quite honestly, nothing terribly exciting."* 'slab/for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/penberg/linux:
mm: SLAB Out-of-memory diagnostics
slab: introduce kmalloc_array()
slub: per cpu partial statistics change
slub: include include for prefetch
slub: Do not hold slub_lock when calling sysfs_slab_add()
slub: prefetch next freelist pointer in slab_alloc()
slab, cleanup: remove unneeded return -
Pull ext4 updates for 3.4 from Ted Ts'o:
"Ext4 commits for 3.3 merge window; mostly cleanups and bug fixesThe changes to export dirty_writeback_interval are from Artem's s_dirt
cleanup patch series. The same is true of the change to remove the
s_dirt helper functions which never got used by anyone in-tree. I've
run these changes by Al Viro, and am carrying them so that Artem can
more easily fix up the rest of the file systems during the next merge
window. (Originally we had hopped to remove the use of s_dirt from
ext4 during this merge window, but his patches had some bugs, so I
ultimately ended dropping them from the ext4 tree.)"* tag 'ext4_for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tytso/ext4: (66 commits)
vfs: remove unused superblock helpers
mm: export dirty_writeback_interval
ext4: remove useless s_dirt assignment
ext4: write superblock only once on unmount
ext4: do not mark superblock as dirty unnecessarily
ext4: correct ext4_punch_hole return codes
ext4: remove restrictive checks for EOFBLOCKS_FL
ext4: always set then trimmed blocks count into len
ext4: fix trimmed block count accunting
ext4: fix start and len arguments handling in ext4_trim_fs()
ext4: update s_free_{inodes,blocks}_count during online resize
ext4: change some printk() calls to use ext4_msg() instead
ext4: avoid output message interleaving in ext4_error_()
ext4: remove trailing newlines from ext4_msg() and ext4_error() messages
ext4: add no_printk argument validation, fix fallout
ext4: remove redundant "EXT4-fs: " from uses of ext4_msg
ext4: give more helpful error message in ext4_ext_rm_leaf()
ext4: remove unused code from ext4_ext_map_blocks()
ext4: rewrite punch hole to use ext4_ext_remove_space()
jbd2: cleanup journal tail after transaction commit
...
25 Mar, 2012
1 commit
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We should only test compaction_suitable if the kernel is built with
CONFIG_COMPACTION, otherwise the stub compaction_suitable function will
always return COMPACT_SKIPPED and send kswapd into an infinite loop.Reported-by: Anton Blanchard
Signed-off-by: Rik van Riel
Signed-off-by: Linus Torvalds
24 Mar, 2012
4 commits
-
Since we no longer need the VM_ALWAYSDUMP flag, let's use the freed bit
for 'VM_NODUMP' flag. The idea is is to add a new madvise() flag:
MADV_DONTDUMP, which can be set by applications to specifically request
memory regions which should not dump core.The specific application I have in mind is qemu: we can add a flag there
that wouldn't dump all of guest memory when qemu dumps core. This flag
might also be useful for security sensitive apps that want to absolutely
make sure that parts of memory are not dumped. To clear the flag use:
MADV_DODUMP.[akpm@linux-foundation.org: s/MADV_NODUMP/MADV_DONTDUMP/, s/MADV_CLEAR_NODUMP/MADV_DODUMP/, per Roland]
[akpm@linux-foundation.org: fix up the architectures which broke]
Signed-off-by: Jason Baron
Acked-by: Roland McGrath
Cc: Chris Metcalf
Cc: Avi Kivity
Cc: Ralf Baechle
Cc: Richard Henderson
Cc: Ivan Kokshaysky
Cc: Matt Turner
Cc: "James E.J. Bottomley"
Cc: Helge Deller
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
The motivation for this patchset was that I was looking at a way for a
qemu-kvm process, to exclude the guest memory from its core dump, which
can be quite large. There are already a number of filter flags in
/proc//coredump_filter, however, these allow one to specify 'types'
of kernel memory, not specific address ranges (which is needed in this
case).Since there are no more vma flags available, the first patch eliminates
the need for the 'VM_ALWAYSDUMP' flag. The flag is used internally by
the kernel to mark vdso and vsyscall pages. However, it is simple
enough to check if a vma covers a vdso or vsyscall page without the need
for this flag.The second patch then replaces the 'VM_ALWAYSDUMP' flag with a new
'VM_NODUMP' flag, which can be set by userspace using new madvise flags:
'MADV_DONTDUMP', and unset via 'MADV_DODUMP'. The core dump filters
continue to work the same as before unless 'MADV_DONTDUMP' is set on the
region.The qemu code which implements this features is at:
http://people.redhat.com/~jbaron/qemu-dump/qemu-dump.patch
In my testing the qemu core dump shrunk from 383MB -> 13MB with this
patch.I also believe that the 'MADV_DONTDUMP' flag might be useful for
security sensitive apps, which might want to select which areas are
dumped.This patch:
The VM_ALWAYSDUMP flag is currently used by the coredump code to
indicate that a vma is part of a vsyscall or vdso section. However, we
can determine if a vma is in one these sections by checking it against
the gate_vma and checking for a non-NULL return value from
arch_vma_name(). Thus, freeing a valuable vma bit.Signed-off-by: Jason Baron
Acked-by: Roland McGrath
Cc: Chris Metcalf
Cc: Avi Kivity
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
Change oom_kill_task() to use do_send_sig_info(SEND_SIG_FORCED) instead
of force_sig(SIGKILL). With the recent changes we do not need force_ to
kill the CLONE_NEWPID tasks.And this is more correct. force_sig() can race with the exiting thread
even if oom_kill_task() checks p->mm != NULL, while
do_send_sig_info(group => true) kille the whole process.Signed-off-by: Oleg Nesterov
Cc: Tejun Heo
Cc: Anton Vorontsov
Cc: "Eric W. Biederman"
Cc: KOSAKI Motohiro
Cc: David Rientjes
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
Fix code duplication in __unmap_hugepage_range(), such as pte_page() and
huge_pte_none().Signed-off-by: Hillf Danton
Cc: Michal Hocko
Cc: KAMEZAWA Hiroyuki
Cc: Hugh Dickins
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
23 Mar, 2012
4 commits
-
Adjusting cc715d99e529 "mm: vmscan: forcibly scan highmem if there are
too many buffer_heads pinning highmem" for -stable reveals that it was
slightly wrong once on top of fe2c2a106663 "vmscan: reclaim at order 0
when compaction is enabled", which specifically adds testorder for the
zone_watermark_ok_safe() test.Signed-off-by: Hugh Dickins
Acked-by: Mel Gorman
Acked-by: Rik van Riel
Cc: Andrew Morton
Signed-off-by: Linus Torvalds -
Pull cleancache changes from Konrad Rzeszutek Wilk:
"This has some patches for the cleancache API that should have been
submitted a _long_ time ago. They are basically cleanups:- rename of flush to invalidate
- moving reporting of statistics into debugfs
- use __read_mostly as necessary.
Oh, and also the MAINTAINERS file change. The files (except the
MAINTAINERS file) have been in #linux-next for months now. The late
addition of MAINTAINERS file is a brain-fart on my side - didn't
realize I needed that just until I was typing this up - and I based
that patch on v3.3 - so the tree is on top of v3.3."* tag 'stable/for-linus-3.4' of git://git.kernel.org/pub/scm/linux/kernel/git/konrad/mm:
MAINTAINERS: Adding cleancache API to the list.
mm: cleancache: Use __read_mostly as appropiate.
mm: cleancache: report statistics via debugfs instead of sysfs.
mm: zcache/tmem/cleancache: s/flush/invalidate/
mm: cleancache: s/flush/invalidate/ -
Pull MCE changes from Ingo Molnar.
* 'x86-mce-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
x86/mce: Fix return value of mce_chrdev_read() when erst is disabled
x86/mce: Convert static array of pointers to per-cpu variables
x86/mce: Replace hard coded hex constants with symbolic defines
x86/mce: Recognise machine check bank signature for data path error
x86/mce: Handle "action required" errors
x86/mce: Add mechanism to safely save information in MCE handler
x86/mce: Create helper function to save addr/misc when needed
HWPOISON: Add code to handle "action required" errors.
HWPOISON: Clean up memory_failure() vs. __memory_failure() -
Merge first batch of patches from Andrew Morton:
"A few misc things and all the MM queue"* emailed from Andrew Morton : (92 commits)
memcg: avoid THP split in task migration
thp: add HPAGE_PMD_* definitions for !CONFIG_TRANSPARENT_HUGEPAGE
memcg: clean up existing move charge code
mm/memcontrol.c: remove unnecessary 'break' in mem_cgroup_read()
mm/memcontrol.c: remove redundant BUG_ON() in mem_cgroup_usage_unregister_event()
mm/memcontrol.c: s/stealed/stolen/
memcg: fix performance of mem_cgroup_begin_update_page_stat()
memcg: remove PCG_FILE_MAPPED
memcg: use new logic for page stat accounting
memcg: remove PCG_MOVE_LOCK flag from page_cgroup
memcg: simplify move_account() check
memcg: remove EXPORT_SYMBOL(mem_cgroup_update_page_stat)
memcg: kill dead prev_priority stubs
memcg: remove PCG_CACHE page_cgroup flag
memcg: let css_get_next() rely upon rcu_read_lock()
cgroup: revert ss_id_lock to spinlock
idr: make idr_get_next() good for rcu_read_lock()
memcg: remove unnecessary thp check in page stat accounting
memcg: remove redundant returns
memcg: enum lru_list lru
...
22 Mar, 2012
21 commits
-
Export 'dirty_writeback_interval' to make it visible to
file-systems. We are going to push superblock management down to
file-systems and get rid of the 'sync_supers' kernel thread completly.Signed-off-by: Artem Bityutskiy
Cc: Al Viro
Signed-off-by: "Theodore Ts'o" -
Currently we can't do task migration among memory cgroups without THP
split, which means processes heavily using THP experience large overhead
in task migration. This patch introduces the code for moving charge of
THP and makes THP more valuable.Signed-off-by: Naoya Horiguchi
Acked-by: Hillf Danton
Cc: Andrea Arcangeli
Acked-by: KAMEZAWA Hiroyuki
Cc: David Rientjes
Cc: Daisuke Nishimura
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
These macros will be used in a later patch, where all usages are expected
to be optimized away without #ifdef CONFIG_TRANSPARENT_HUGEPAGE. But to
detect unexpected usages, we convert the existing BUG() to BUILD_BUG().[akpm@linux-foundation.org: fix build in mm/pgtable-generic.c]
Signed-off-by: Naoya Horiguchi
Acked-by: Hillf Danton
Reviewed-by: Andrea Arcangeli
Reviewed-by: KAMEZAWA Hiroyuki
Acked-by: David Rientjes
Cc: Daisuke Nishimura
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
- Replace lengthy function name is_target_pte_for_mc() with a shorter
one in order to avoid ugly line breaks.- explicitly use MC_TARGET_* instead of simply using integers.
Signed-off-by: Naoya Horiguchi
Cc: Andrea Arcangeli
Cc: KAMEZAWA Hiroyuki
Cc: Daisuke Nishimura
Cc: Hillf Danton
Cc: David Rientjes
Acked-by: Hillf Danton
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
Signed-off-by: Jie Liu
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
In the following code:
if (type == _MEM)
thresholds = &memcg->thresholds;
else if (type == _MEMSWAP)
thresholds = &memcg->memsw_thresholds;
else
BUG();BUG_ON(!thresholds);
The BUG_ON() seems redundant.
Signed-off-by: Anton Vorontsov
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
A grammatical fix.
Cc: KAMEZAWA Hiroyuki
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
mem_cgroup_begin_update_page_stat() should be very fast because it's
called very frequently. Now, it needs to look up page_cgroup and its
memcg....this is slow.This patch adds a global variable to check "any memcg is moving or not".
With this, the caller doesn't need to visit page_cgroup and memcg.Here is a test result. A test program makes page faults onto a file,
MAP_SHARED and makes each page's page_mapcount(page) > 1, and free the
range by madvise() and page fault again. This program causes 26214400
times of page fault onto a file(size was 1G.) and shows shows the cost of
mem_cgroup_begin_update_page_stat().Before this patch for mem_cgroup_begin_update_page_stat()
[kamezawa@bluextal test]$ time ./mmap 1G
real 0m21.765s
user 0m5.999s
sys 0m15.434s27.46% mmap mmap [.] reader
21.15% mmap [kernel.kallsyms] [k] page_fault
9.17% mmap [kernel.kallsyms] [k] filemap_fault
2.96% mmap [kernel.kallsyms] [k] __do_fault
2.83% mmap [kernel.kallsyms] [k] __mem_cgroup_begin_update_page_statAfter this patch
[root@bluextal test]# time ./mmap 1G
real 0m21.373s
user 0m6.113s
sys 0m15.016sIn usual path, calls to __mem_cgroup_begin_update_page_stat() goes away.
Note: we may be able to remove this optimization in future if
we can get pointer to memcg directly from struct page.[akpm@linux-foundation.org: don't return a void]
Signed-off-by: KAMEZAWA Hiroyuki
Acked-by: Greg Thelen
Acked-by: Johannes Weiner
Cc: Michal Hocko
Cc: KOSAKI Motohiro
Cc: Ying Han
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
With the new lock scheme for updating memcg's page stat, we don't need a
flag PCG_FILE_MAPPED which was duplicated information of page_mapped().[hughd@google.com: cosmetic fix]
[hughd@google.com: add comment to MEM_CGROUP_CHARGE_TYPE_MAPPED case in __mem_cgroup_uncharge_common()]
Signed-off-by: KAMEZAWA Hiroyuki
Acked-by: Greg Thelen
Acked-by: Johannes Weiner
Cc: Michal Hocko
Cc: KOSAKI Motohiro
Cc: Ying Han
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
Now, page-stat-per-memcg is recorded into per page_cgroup flag by
duplicating page's status into the flag. The reason is that memcg has a
feature to move a page from a group to another group and we have race
between "move" and "page stat accounting",Under current logic, assume CPU-A and CPU-B. CPU-A does "move" and CPU-B
does "page stat accounting".When CPU-A goes 1st,
CPU-A CPU-B
update "struct page" info.
move_lock_mem_cgroup(memcg)
see pc->flags
copy page stat to new group
overwrite pc->mem_cgroup.
move_unlock_mem_cgroup(memcg)
move_lock_mem_cgroup(mem)
set pc->flags
update page stat accounting
move_unlock_mem_cgroup(mem)stat accounting is guarded by move_lock_mem_cgroup() and "move" logic
(CPU-A) doesn't see changes in "struct page" information.But it's costly to have the same information both in 'struct page' and
'struct page_cgroup'. And, there is a potential problem.For example, assume we have PG_dirty accounting in memcg.
PG_..is a flag for struct page.
PCG_ is a flag for struct page_cgroup.
(This is just an example. The same problem can be found in any
kind of page stat accounting.)CPU-A CPU-B
TestSet PG_dirty
(delay) TestClear PG_dirty
if (TestClear(PCG_dirty))
memcg->nr_dirty--
if (TestSet(PCG_dirty))
memcg->nr_dirty++Here, memcg->nr_dirty = +1, this is wrong. This race was reported by Greg
Thelen . Now, only FILE_MAPPED is supported but
fortunately, it's serialized by page table lock and this is not real bug,
_now_,If this potential problem is caused by having duplicated information in
struct page and struct page_cgroup, we may be able to fix this by using
original 'struct page' information. But we'll have a problem in "move
account"Assume we use only PG_dirty.
CPU-A CPU-B
TestSet PG_dirty
(delay) move_lock_mem_cgroup()
if (PageDirty(page))
new_memcg->nr_dirty++
pc->mem_cgroup = new_memcg;
move_unlock_mem_cgroup()
move_lock_mem_cgroup()
memcg = pc->mem_cgroup
new_memcg->nr_dirty++accounting information may be double-counted. This was original reason to
have PCG_xxx flags but it seems PCG_xxx has another problem.I think we need a bigger lock as
move_lock_mem_cgroup(page)
TestSetPageDirty(page)
update page stats (without any checks)
move_unlock_mem_cgroup(page)This fixes both of problems and we don't have to duplicate page flag into
page_cgroup. Please note: move_lock_mem_cgroup() is held only when there
are possibility of "account move" under the system. So, in most path,
status update will go without atomic locks.This patch introduces mem_cgroup_begin_update_page_stat() and
mem_cgroup_end_update_page_stat() both should be called at modifying
'struct page' information if memcg takes care of it. asmem_cgroup_begin_update_page_stat()
modify page information
mem_cgroup_update_page_stat()
=> never check any 'struct page' info, just update counters.
mem_cgroup_end_update_page_stat().This patch is slow because we need to call begin_update_page_stat()/
end_update_page_stat() regardless of accounted will be changed or not. A
following patch adds an easy optimization and reduces the cost.[akpm@linux-foundation.org: s/lock/locked/]
[hughd@google.com: fix deadlock by avoiding stat lock when anon]
Signed-off-by: KAMEZAWA Hiroyuki
Cc: Greg Thelen
Acked-by: Johannes Weiner
Cc: Michal Hocko
Cc: KOSAKI Motohiro
Cc: Ying Han
Signed-off-by: Hugh Dickins
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
PCG_MOVE_LOCK is used for bit spinlock to avoid race between overwriting
pc->mem_cgroup and page statistics accounting per memcg. This lock helps
to avoid the race but the race is very rare because moving tasks between
cgroup is not a usual job. So, it seems using 1bit per page is too
costly.This patch changes this lock as per-memcg spinlock and removes
PCG_MOVE_LOCK.If smaller lock is required, we'll be able to add some hashes but I'd like
to start from this.Signed-off-by: KAMEZAWA Hiroyuki
Acked-by: Greg Thelen
Cc: Johannes Weiner
Cc: Michal Hocko
Cc: KOSAKI Motohiro
Cc: Ying Han
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
In memcg, for avoiding take-lock-irq-off at accessing page_cgroup, a
logic, flag + rcu_read_lock(), is used. This works as followingCPU-A CPU-B
rcu_read_lock()
set flag
if(flag is set)
take heavy lock
do job.
synchronize_rcu() rcu_read_unlock()
take heavy lock.In recent discussion, it's argued that using per-cpu value for this flag
just complicates the code because 'set flag' is very rare.This patch changes 'flag' implementation from percpu to atomic_t. This
will be much simpler.Signed-off-by: KAMEZAWA Hiroyuki
Acked-by: Greg Thelen
Cc: Johannes Weiner
Cc: Michal Hocko
Cc: KOSAKI Motohiro
Cc: Ying Han
Cc: "Paul E. McKenney"
Acked-by: Johannes Weiner
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
As described in the log, I guess EXPORT was for preparing dirty
accounting. But _now_, we don't need to export this. Remove this for
now.Signed-off-by: KAMEZAWA Hiroyuki
Reviewed-by: Greg Thelen
Cc: Johannes Weiner
Cc: Michal Hocko
Cc: KOSAKI Motohiro
Cc: Ying Han
Acked-by: Johannes Weiner
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
We record 'the page is cache' with the PCG_CACHE bit in page_cgroup.
Here, "CACHE" means anonymous user pages (and SwapCache). This doesn't
include shmem.Considering callers, at charge/uncharge, the caller should know what the
page is and we don't need to record it by using one bit per page.This patch removes PCG_CACHE bit and make callers of
mem_cgroup_charge_statistics() to specify what the page is.About page migration: Mapping of the used page is not touched during migra
tion (see page_remove_rmap) so we can rely on it and push the correct
charge type down to __mem_cgroup_uncharge_common from end_migration for
unused page. The force flag was misleading was abused for skipping the
needless page_mapped() / PageCgroupMigration() check, as we know the
unused page is no longer mapped and cleared the migration flag just a few
lines up. But doing the checks is no biggie and it's not worth adding
another flag just to skip them.[akpm@linux-foundation.org: checkpatch fixes]
[hughd@google.com: fix PageAnon uncharging]
Signed-off-by: KAMEZAWA Hiroyuki
Acked-by: Michal Hocko
Acked-by: Johannes Weiner
Cc: Hugh Dickins
Cc: Ying Han
Acked-by: Johannes Weiner
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
Commit e94c8a9cbce1 ("memcg: make mem_cgroup_split_huge_fixup() more
efficient") removed move_lock_page_cgroup(). So we do not have to check
PageTransHuge in mem_cgroup_update_page_stat() and fallback into the
locked accounting because both move_account() and thp split are done
with compound_lock so they cannot race.The race between update vs. move is protected by mem_cgroup_stealed.
PageTransHuge pages shouldn't appear in this code path currently because
we are tracking only file pages at the moment but later we are planning
to track also other pages (e.g. mlocked ones).Signed-off-by: KAMEZAWA Hiroyuki
Cc: Johannes Weiner
Cc: Andrea Arcangeli
Reviewed-by: Acked-by: Michal Hocko
Cc: David Rientjes
Acked-by: Ying Han
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
Remove redundant returns from ends of functions, and one blank line.
Signed-off-by: Hugh Dickins
Reviewed-by: KOSAKI Motohiro
Acked-by: Kirill A. Shutemov
Acked-by: Michal Hocko
Acked-by: KAMEZAWA Hiroyuki
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
Mostly we use "enum lru_list lru": change those few "l"s to "lru"s.
Signed-off-by: Hugh Dickins
Reviewed-by: KOSAKI Motohiro
Acked-by: Kirill A. Shutemov
Acked-by: Michal Hocko
Acked-by: KAMEZAWA Hiroyuki
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
I never understood why we need a MEM_CGROUP_ZSTAT(mz, idx) macro to
obscure the LRU counts. For easier searching? So call it lru_size
rather than bare count (lru_length sounds better, but would be wrong,
since each huge page raises lru_size hugely).Signed-off-by: Hugh Dickins
Acked-by: Kirill A. Shutemov
Acked-by: KAMEZAWA Hiroyuki
Cc: Michal Hocko
Cc: KOSAKI Motohiro
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
Replace mem and mem_cont stragglers in memcontrol.c by memcg.
Signed-off-by: Hugh Dickins
Reviewed-by: KOSAKI Motohiro
Acked-by: Kirill A. Shutemov
Acked-by: Michal Hocko
Acked-by: KAMEZAWA Hiroyuki
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
When swapon() was not passed the SWAP_FLAG_DISCARD option, sys_swapon()
will still perform a discard operation. This can cause problems if
discard is slow or buggy.Reverse the order of the check so that a discard operation is performed
only if the sys_swapon() caller is attempting to enable discard.Signed-off-by: Shaohua Li
Reported-by: Holger Kiehl
Tested-by: Holger Kiehl
Cc: Hugh Dickins
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
Reset the reclaim mode in shrink_active_list() to RECLAIM_MODE_SINGLE |
RECLAIM_MODE_ASYNC. (sync/async sign is used only in shrink_page_list
and does not affect shrink_active_list)Currenly shrink_active_list() sometimes works in lumpy-reclaim mode, if
RECLAIM_MODE_LUMPYRECLAIM is left over from an earlier
shrink_inactive_list(). Meanwhile, in age_active_anon()
sc->reclaim_mode is totally zero. So the current behavior is too
complex and confusing, and this looks like bug.In general, shrink_active_list() populates the inactive list for the
next shrink_inactive_list(). Lumpy shring_inactive_list() isolates
pages around the chosen one from both the active and inactive lists.
So, there is no reason for lumpy isolation in shrink_active_list().See also: https://lkml.org/lkml/2012/3/15/583
Signed-off-by: Konstantin Khlebnikov
Proposed-by: Hugh Dickins
Acked-by: Johannes Weiner
Cc: Rik van Riel
Cc: Minchan Kim
Cc: Mel Gorman
Cc: KAMEZAWA Hiroyuki
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
