NOTE: This is very heavily based on similar logic in autonuma. It should
be signed off by Andrea but because there was no standalone
patch and it's sufficiently different from what he did that
the signed-off is omitted. Will be added back if requested.
If a large number of pages are misplaced then the memory bus can be
saturated just migrating pages between nodes. This patch rate-limits
the amount of memory that can be migrating between nodes.
Signed-off-by: Mel Gorman <mgorman@suse.de>
It is tricky to quantify the basic cost of automatic NUMA placement in a
meaningful manner. This patch adds some vmstats that can be used as part
of a basic costing model.
u = basic unit = sizeof(void *)
Ca = cost of struct page access = sizeof(struct page) / u
Cpte = Cost PTE access = Ca
Cupdate = Cost PTE update = (2 * Cpte) + (2 * Wlock)
where Cpte is incurred twice for a read and a write and Wlock
is a constant representing the cost of taking or releasing a
lock
Cnumahint = Cost of a minor page fault = some high constant e.g. 1000
Cpagerw = Cost to read or write a full page = Ca + PAGE_SIZE/u
Ci = Cost of page isolation = Ca + Wi
where Wi is a constant that should reflect the approximate cost
of the locking operation
Cpagecopy = Cpagerw + (Cpagerw * Wnuma) + Ci + (Ci * Wnuma)
where Wnuma is the approximate NUMA factor. 1 is local. 1.2
would imply that remote accesses are 20% more expensive
Balancing cost = Cpte * numa_pte_updates +
Cnumahint * numa_hint_faults +
Ci * numa_pages_migrated +
Cpagecopy * numa_pages_migrated
Note that numa_pages_migrated is used as a measure of how many pages
were isolated even though it would miss pages that failed to migrate. A
vmstat counter could have been added for it but the isolation cost is
pretty marginal in comparison to the overall cost so it seemed overkill.
The ideal way to measure automatic placement benefit would be to count
the number of remote accesses versus local accesses and do something like
benefit = (remote_accesses_before - remove_access_after) * Wnuma
but the information is not readily available. As a workload converges, the
expection would be that the number of remote numa hints would reduce to 0.
convergence = numa_hint_faults_local / numa_hint_faults
where this is measured for the last N number of
numa hints recorded. When the workload is fully
converged the value is 1.
This can measure if the placement policy is converging and how fast it is
doing it.
Signed-off-by: Mel Gorman <mgorman@suse.de>
Acked-by: Rik van Riel <riel@redhat.com>
If we have to avoid migrating to a node that is nearly full, put page
and return zero.
Signed-off-by: Hillf Danton <dhillf@gmail.com>
Signed-off-by: Mel Gorman <mgorman@suse.de>
Note: This was originally based on Peter's patch "mm/migrate: Introduce
migrate_misplaced_page()" but borrows extremely heavily from Andrea's
"autonuma: memory follows CPU algorithm and task/mm_autonuma stats
collection". The end result is barely recognisable so signed-offs
had to be dropped. If original authors are ok with it, I'll
re-add the signed-off-bys.
Add migrate_misplaced_page() which deals with migrating pages from
faults.
Based-on-work-by: Lee Schermerhorn <Lee.Schermerhorn@hp.com>
Based-on-work-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Based-on-work-by: Andrea Arcangeli <aarcange@redhat.com>
Signed-off-by: Mel Gorman <mgorman@suse.de>
Reviewed-by: Rik van Riel <riel@redhat.com>
The pgmigrate_success and pgmigrate_fail vmstat counters tells the user
about migration activity but not the type or the reason. This patch adds
a tracepoint to identify the type of page migration and why the page is
being migrated.
Signed-off-by: Mel Gorman <mgorman@suse.de>
Reviewed-by: Rik van Riel <riel@redhat.com>
The compact_pages_moved and compact_pagemigrate_failed events are
convenient for determining if compaction is active and to what
degree migration is succeeding but it's at the wrong level. Other
users of migration may also want to know if migration is working
properly and this will be particularly true for any automated
NUMA migration. This patch moves the counters down to migration
with the new events called pgmigrate_success and pgmigrate_fail.
The compact_blocks_moved counter is removed because while it was
useful for debugging initially, it's worthless now as no meaningful
conclusions can be drawn from its value.
Signed-off-by: Mel Gorman <mgorman@suse.de>
Reviewed-by: Rik van Riel <riel@redhat.com>
Compaction (and page migration in general) can currently be hindered
through pages being owned by memory cgroups that are at their limits and
unreclaimable.
The reason is that the replacement page is being charged against the limit
while the page being replaced is also still charged. But this seems
unnecessary, given that only one of the two pages will still be in use
after migration finishes.
This patch changes the memcg migration sequence so that the replacement
page is not charged. Whatever page is still in use after successful or
failed migration gets to keep the charge of the page that was going to be
replaced.
The replacement page will still show up temporarily in the rss/cache
statistics, this can be fixed in a later patch as it's less urgent.
Reported-by: David Rientjes <rientjes@google.com>
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Acked-by: Michal Hocko <mhocko@suse.cz>
Cc: Hugh Dickins <hughd@google.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Wanpeng Li <liwp.linux@gmail.com>
Cc: Mel Gorman <mel@csn.ul.ie>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
New tmpfs use of !PageUptodate pages for fallocate() is triggering the
WARNING: at mm/page-writeback.c:1990 when __set_page_dirty_nobuffers()
is called from migrate_page_copy() for compaction.
It is anomalous that migration should use __set_page_dirty_nobuffers()
on an address_space that does not participate in dirty and writeback
accounting; and this has also been observed to insert surprising dirty
tags into a tmpfs radix_tree, despite tmpfs not using tags at all.
We should probably give migrate_page_copy() a better way to preserve the
tag and migrate accounting info, when mapping_cap_account_dirty(). But
that needs some more work: so in the interim, avoid the warning by using
a simple SetPageDirty on PageSwapBacked pages.
Reported-and-tested-by: Dave Jones <davej@redhat.com>
Signed-off-by: Hugh Dickins <hughd@google.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Pull user namespace enhancements from Eric Biederman:
"This is a course correction for the user namespace, so that we can
reach an inexpensive, maintainable, and reasonably complete
implementation.
Highlights:
- Config guards make it impossible to enable the user namespace and
code that has not been converted to be user namespace safe.
- Use of the new kuid_t type ensures the if you somehow get past the
config guards the kernel will encounter type errors if you enable
user namespaces and attempt to compile in code whose permission
checks have not been updated to be user namespace safe.
- All uids from child user namespaces are mapped into the initial
user namespace before they are processed. Removing the need to add
an additional check to see if the user namespace of the compared
uids remains the same.
- With the user namespaces compiled out the performance is as good or
better than it is today.
- For most operations absolutely nothing changes performance or
operationally with the user namespace enabled.
- The worst case performance I could come up with was timing 1
billion cache cold stat operations with the user namespace code
enabled. This went from 156s to 164s on my laptop (or 156ns to
164ns per stat operation).
- (uid_t)-1 and (gid_t)-1 are reserved as an internal error value.
Most uid/gid setting system calls treat these value specially
anyway so attempting to use -1 as a uid would likely cause
entertaining failures in userspace.
- If setuid is called with a uid that can not be mapped setuid fails.
I have looked at sendmail, login, ssh and every other program I
could think of that would call setuid and they all check for and
handle the case where setuid fails.
- If stat or a similar system call is called from a context in which
we can not map a uid we lie and return overflowuid. The LFS
experience suggests not lying and returning an error code might be
better, but the historical precedent with uids is different and I
can not think of anything that would break by lying about a uid we
can't map.
- Capabilities are localized to the current user namespace making it
safe to give the initial user in a user namespace all capabilities.
My git tree covers all of the modifications needed to convert the core
kernel and enough changes to make a system bootable to runlevel 1."
Fix up trivial conflicts due to nearby independent changes in fs/stat.c
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace: (46 commits)
userns: Silence silly gcc warning.
cred: use correct cred accessor with regards to rcu read lock
userns: Convert the move_pages, and migrate_pages permission checks to use uid_eq
userns: Convert cgroup permission checks to use uid_eq
userns: Convert tmpfs to use kuid and kgid where appropriate
userns: Convert sysfs to use kgid/kuid where appropriate
userns: Convert sysctl permission checks to use kuid and kgids.
userns: Convert proc to use kuid/kgid where appropriate
userns: Convert ext4 to user kuid/kgid where appropriate
userns: Convert ext3 to use kuid/kgid where appropriate
userns: Convert ext2 to use kuid/kgid where appropriate.
userns: Convert devpts to use kuid/kgid where appropriate
userns: Convert binary formats to use kuid/kgid where appropriate
userns: Add negative depends on entries to avoid building code that is userns unsafe
userns: signal remove unnecessary map_cred_ns
userns: Teach inode_capable to understand inodes whose uids map to other namespaces.
userns: Fail exec for suid and sgid binaries with ids outside our user namespace.
userns: Convert stat to return values mapped from kuids and kgids
userns: Convert user specfied uids and gids in chown into kuids and kgid
userns: Use uid_eq gid_eq helpers when comparing kuids and kgids in the vfs
...
Migration functions perform the rcu_read_unlock too early. As a result
the task pointed to may change from under us. This can result in an oops,
as reported by Dave Hansen in https://lkml.org/lkml/2012/2/23/302.
The following patch extend the period of the rcu_read_lock until after the
permissions checks are done. We also take a refcount so that the task
reference is stable when calling security check functions and performing
cpuset node validation (which takes a mutex).
The refcount is dropped before actual page migration occurs so there is no
change to the refcounts held during page migration.
Also move the determination of the mm of the task struct to immediately
before the do_migrate*() calls so that it is clear that we switch from
handling the task during permission checks to the mm for the actual
migration. Since the determination is only done once and we then no
longer use the task_struct we can be sure that we operate on a specific
address space that will not change from under us.
[akpm@linux-foundation.org: checkpatch fixes]
Signed-off-by: Christoph Lameter <cl@linux.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Reported-by: Dave Hansen <dave@linux.vnet.ibm.com>
Cc: Mel Gorman <mel@csn.ul.ie>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Hugh Dickins <hughd@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
When moving tasks from old memcg (with move_charge_at_immigrate on new
memcg), followed by removal of old memcg, hit General Protection Fault in
mem_cgroup_lru_del_list() (called from release_pages called from
free_pages_and_swap_cache from tlb_flush_mmu from tlb_finish_mmu from
exit_mmap from mmput from exit_mm from do_exit).
Somewhat reproducible, takes a few hours: the old struct mem_cgroup has
been freed and poisoned by SLAB_DEBUG, but mem_cgroup_lru_del_list() is
still trying to update its stats, and take page off lru before freeing.
A task, or a charge, or a page on lru: each secures a memcg against
removal. In this case, the last task has been moved out of the old memcg,
and it is exiting: anonymous pages are uncharged one by one from the
memcg, as they are zapped from its pagetables, so the charge gets down to
0; but the pages themselves are queued in an mmu_gather for freeing.
Most of those pages will be on lru (and force_empty is careful to
lru_add_drain_all, to add pages from pagevec to lru first), but not
necessarily all: perhaps some have been isolated for page reclaim, perhaps
some isolated for other reasons. So, force_empty may find no task, no
charge and no page on lru, and let the removal proceed.
There would still be no problem if these pages were immediately freed; but
typically (and the put_page_testzero protocol demands it) they have to be
added back to lru before they are found freeable, then removed from lru
and freed. We don't see the issue when adding, because the
mem_cgroup_iter() loops keep their own reference to the memcg being
scanned; but when it comes to mem_cgroup_lru_del_list().
I believe this was not an issue in v3.2: there, PageCgroupAcctLRU and
PageCgroupUsed flags were used (like a trick with mirrors) to deflect view
of pc->mem_cgroup to the stable root_mem_cgroup when neither set.
38c5d72f3e ("memcg: simplify LRU handling by new rule") mercifully
removed those convolutions, but left this General Protection Fault.
But it's surprisingly easy to restore the old behaviour: just check
PageCgroupUsed in mem_cgroup_lru_add_list() (which decides on which lruvec
to add), and reset pc to root_mem_cgroup if page is uncharged. A risky
change? just going back to how it worked before; testing, and an audit of
uses of pc->mem_cgroup, show no problem.
And there's a nice bonus: with mem_cgroup_lru_add_list() itself making
sure that an uncharged page goes to root lru, mem_cgroup_reset_owner() no
longer has any purpose, and we can safely revert 4e5f01c2b9 ("memcg:
clear pc->mem_cgroup if necessary").
Calling update_page_reclaim_stat() after add_page_to_lru_list() in swap.c
is not strictly necessary: the lru_lock there, with RCU before memcg
structures are freed, makes mem_cgroup_get_reclaim_stat_from_page safe
without that; but it seems cleaner to rely on one dependency less.
Signed-off-by: Hugh Dickins <hughd@google.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Konstantin Khlebnikov <khlebnikov@openvz.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This patch adds a lightweight sync migrate operation MIGRATE_SYNC_LIGHT
mode that avoids writing back pages to backing storage. Async compaction
maps to MIGRATE_ASYNC while sync compaction maps to MIGRATE_SYNC_LIGHT.
For other migrate_pages users such as memory hotplug, MIGRATE_SYNC is
used.
This avoids sync compaction stalling for an excessive length of time,
particularly when copying files to a USB stick where there might be a
large number of dirty pages backed by a filesystem that does not support
->writepages.
[aarcange@redhat.com: This patch is heavily based on Andrea's work]
[akpm@linux-foundation.org: fix fs/nfs/write.c build]
[akpm@linux-foundation.org: fix fs/btrfs/disk-io.c build]
Signed-off-by: Mel Gorman <mgorman@suse.de>
Reviewed-by: Rik van Riel <riel@redhat.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Minchan Kim <minchan.kim@gmail.com>
Cc: Dave Jones <davej@redhat.com>
Cc: Jan Kara <jack@suse.cz>
Cc: Andy Isaacson <adi@hexapodia.org>
Cc: Nai Xia <nai.xia@gmail.com>
Cc: Johannes Weiner <jweiner@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Asynchronous compaction is used when allocating transparent hugepages to
avoid blocking for long periods of time. Due to reports of stalling,
there was a debate on disabling synchronous compaction but this severely
impacted allocation success rates. Part of the reason was that many dirty
pages are skipped in asynchronous compaction by the following check;
if (PageDirty(page) && !sync &&
mapping->a_ops->migratepage != migrate_page)
rc = -EBUSY;
This skips over all mapping aops using buffer_migrate_page() even though
it is possible to migrate some of these pages without blocking. This
patch updates the ->migratepage callback with a "sync" parameter. It is
the responsibility of the callback to fail gracefully if migration would
block.
Signed-off-by: Mel Gorman <mgorman@suse.de>
Reviewed-by: Rik van Riel <riel@redhat.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Minchan Kim <minchan.kim@gmail.com>
Cc: Dave Jones <davej@redhat.com>
Cc: Jan Kara <jack@suse.cz>
Cc: Andy Isaacson <adi@hexapodia.org>
Cc: Nai Xia <nai.xia@gmail.com>
Cc: Johannes Weiner <jweiner@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This is a preparation before removing a flag PCG_ACCT_LRU in page_cgroup
and reducing atomic ops/complexity in memcg LRU handling.
In some cases, pages are added to lru before charge to memcg and pages
are not classfied to memory cgroup at lru addtion. Now, the lru where
the page should be added is determined a bit in page_cgroup->flags and
pc->mem_cgroup. I'd like to remove the check of flag.
To handle the case pc->mem_cgroup may contain stale pointers if pages
are added to LRU before classification. This patch resets
pc->mem_cgroup to root_mem_cgroup before lru additions.
[akpm@linux-foundation.org: fix CONFIG_CGROUP_MEM_CONT=n build]
[hughd@google.com: fix CONFIG_CGROUP_MEM_RES_CTLR=y CONFIG_CGROUP_MEM_RES_CTLR_SWAP=n build]
[akpm@linux-foundation.org: ksm.c needs memcontrol.h, per Michal]
[hughd@google.com: stop oops in mem_cgroup_reset_owner()]
[hughd@google.com: fix page migration to reset_owner]
Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Miklos Szeredi <mszeredi@suse.cz>
Acked-by: Michal Hocko <mhocko@suse.cz>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Ying Han <yinghan@google.com>
Signed-off-by: Hugh Dickins <hughd@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
migrate_page_move_mapping() drops a reference from the old page after
unfreezing its counter. Both operations can be merged into a single
atomic operation by directly unfreezing to one less reference.
The same applies to migrate_huge_page_move_mapping().
Signed-off-by: Jacobo Giralt <jacobo.giralt@gmail.com>
Cc: Mel Gorman <mel@csn.ul.ie>
Cc: Minchan Kim <minchan.kim@gmail.com>
Cc: Johannes Weiner <jweiner@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* 'modsplit-Oct31_2011' of git://git.kernel.org/pub/scm/linux/kernel/git/paulg/linux: (230 commits)
Revert "tracing: Include module.h in define_trace.h"
irq: don't put module.h into irq.h for tracking irqgen modules.
bluetooth: macroize two small inlines to avoid module.h
ip_vs.h: fix implicit use of module_get/module_put from module.h
nf_conntrack.h: fix up fallout from implicit moduleparam.h presence
include: replace linux/module.h with "struct module" wherever possible
include: convert various register fcns to macros to avoid include chaining
crypto.h: remove unused crypto_tfm_alg_modname() inline
uwb.h: fix implicit use of asm/page.h for PAGE_SIZE
pm_runtime.h: explicitly requires notifier.h
linux/dmaengine.h: fix implicit use of bitmap.h and asm/page.h
miscdevice.h: fix up implicit use of lists and types
stop_machine.h: fix implicit use of smp.h for smp_processor_id
of: fix implicit use of errno.h in include/linux/of.h
of_platform.h: delete needless include <linux/module.h>
acpi: remove module.h include from platform/aclinux.h
miscdevice.h: delete unnecessary inclusion of module.h
device_cgroup.h: delete needless include <linux/module.h>
net: sch_generic remove redundant use of <linux/module.h>
net: inet_timewait_sock doesnt need <linux/module.h>
...
Fix up trivial conflicts (other header files, and removal of the ab3550 mfd driver) in
- drivers/media/dvb/frontends/dibx000_common.c
- drivers/media/video/{mt9m111.c,ov6650.c}
- drivers/mfd/ab3550-core.c
- include/linux/dmaengine.h
Mel Gorman
Peter Zijlstra
Johannes Weiner
Aneesh Kumar K.V
Hugh Dickins
Linus Torvalds
Eric W. Biederman
Sasha Levin
Christoph Lameter
Konstantin Khlebnikov
KAMEZAWA Hiroyuki
Wang Sheng-Hui
Jacobo Giralt
Hillf Danton
Minchan Kim