linux.git/mm/memcontrol.c, branch v2.6.30

memcg: fix build warning and avoid checking for mem != null again and again

2009-05-29T15:40:03+00:00

Fix build warning, "mem_cgroup_is_obsolete defined but not used" when
CONFIG_DEBUG_VM is not set.  Also avoid checking for !mem again and again.

Signed-off-by: Nikanth Karthikesan 
Acked-by: Pekka Enberg 
Acked-by: KAMEZAWA Hiroyuki 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

memcg: fix deadlock between lock_page_cgroup and mapping tree_lock

2009-05-29T15:40:02+00:00

mapping->tree_lock can be acquired from interrupt context.  Then,
following dead lock can occur.

Assume "A" as a page.

 CPU0:
       lock_page_cgroup(A)
		interrupted
			-> take mapping->tree_lock.
 CPU1:
       take mapping->tree_lock
		-> lock_page_cgroup(A)

This patch tries to fix above deadlock by moving memcg's hook to out of
mapping->tree_lock.  charge/uncharge of pagecache/swapcache is protected
by page lock, not tree_lock.

After this patch, lock_page_cgroup() is not called under mapping->tree_lock.

Signed-off-by: KAMEZAWA Hiroyuki 
Signed-off-by: Daisuke Nishimura 
Cc: Balbir Singh 
Cc: Daisuke Nishimura 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

memcg: fix mem_cgroup_shrink_usage()

2009-05-02T22:36:09+00:00

Current mem_cgroup_shrink_usage() has two problems.

1. It doesn't call mem_cgroup_out_of_memory and doesn't update
   last_oom_jiffies, so pagefault_out_of_memory invokes global OOM.

2. Considering hierarchy, shrinking has to be done from the
   mem_over_limit, not from the memcg which the page would be charged to.

mem_cgroup_try_charge_swapin() does all of these things properly, so we
use it and call cancel_charge_swapin when it succeeded.

The name of "shrink_usage" is not appropriate for this behavior, so we
change it too.

Signed-off-by: Daisuke Nishimura 
Acked-by: KAMEZAWA Hiroyuki 
Cc: Li Zefan 
Cc: Paul Menage 
Cc: Dhaval Giani 
Cc: Daisuke Nishimura 
Cc: YAMAMOTO Takashi 
Cc: KOSAKI Motohiro 
Cc: David Rientjes 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

memcg: fix try_get_mem_cgroup_from_swapcache()

2009-05-02T22:36:09+00:00

This is a bugfix for commit 3c776e64660028236313f0e54f3a9945764422df
("memcg: charge swapcache to proper memcg").

Used bit of swapcache is solid under page lock, but considering
move_account, pc->mem_cgroup is not.

We need lock_page_cgroup() anyway.

Signed-off-by: Daisuke Nishimura 
Acked-by: KAMEZAWA Hiroyuki 
Cc: Balbir Singh 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

memcg: remove warning when CONFIG_DEBUG_VM=n

2009-04-13T22:04:32+00:00

mm/memcontrol.c:318: warning: `mem_cgroup_is_obsolete' defined but not used

[akpm@linux-foundation.org: simplify as suggested by Balbir]
Signed-off-by: KAMEZAWA Hiroyuki 
Reviewed-by: Balbir Singh 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

memcg: cleanup cache_charge

2009-04-03T02:04:56+00:00

Current mem_cgroup_cache_charge is a bit complicated especially
in the case of shmem's swap-in.

This patch cleans it up by using try_charge_swapin and commit_charge_swapin.

Signed-off-by: Daisuke Nishimura 
Acked-by: KAMEZAWA Hiroyuki 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

cgroups: use css id in swap cgroup for saving memory v5

2009-04-03T02:04:56+00:00

Try to use CSS ID for records in swap_cgroup.  By this, on 64bit machine,
size of swap_cgroup goes down to 2 bytes from 8bytes.

This means, when 2GB of swap is equipped, (assume the page size is 4096bytes)

	From size of swap_cgroup = 2G/4k * 8 = 4Mbytes.
	To   size of swap_cgroup = 2G/4k * 2 = 1Mbytes.

Reduction is large.  Of course, there are trade-offs.  This CSS ID will
add overhead to swap-in/swap-out/swap-free.

But in general,
  - swap is a resource which the user tend to avoid use.
  - If swap is never used, swap_cgroup area is not used.
  - Reading traditional manuals, size of swap should be proportional to
    size of memory. Memory size of machine is increasing now.

I think reducing size of swap_cgroup makes sense.

Note:
  - ID->CSS lookup routine has no locks, it's under RCU-Read-Side.
  - memcg can be obsolete at rmdir() but not freed while refcnt from
    swap_cgroup is available.

Changelog v4->v5:
 - reworked on to memcg-charge-swapcache-to-proper-memcg.patch
Changlog ->v4:
 - fixed not configured case.
 - deleted unnecessary comments.
 - fixed NULL pointer bug.
 - fixed message in dmesg.

[nishimura@mxp.nes.nec.co.jp: css_tryget can be called twice in !PageCgroupUsed case]
Signed-off-by: KAMEZAWA Hiroyuki 
Cc: Li Zefan 
Cc: Balbir Singh 
Cc: Paul Menage 
Cc: Hugh Dickins 
Signed-off-by: Daisuke Nishimura 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

memcg: charge swapcache to proper memcg

2009-04-03T02:04:56+00:00

memcg_test.txt says at 4.1:

	This swap-in is one of the most complicated work. In do_swap_page(),
	following events occur when pte is unchanged.

	(1) the page (SwapCache) is looked up.
	(2) lock_page()
	(3) try_charge_swapin()
	(4) reuse_swap_page() (may call delete_swap_cache())
	(5) commit_charge_swapin()
	(6) swap_free().

	Considering following situation for example.

	(A) The page has not been charged before (2) and reuse_swap_page()
	    doesn't call delete_from_swap_cache().
	(B) The page has not been charged before (2) and reuse_swap_page()
	    calls delete_from_swap_cache().
	(C) The page has been charged before (2) and reuse_swap_page() doesn't
	    call delete_from_swap_cache().
	(D) The page has been charged before (2) and reuse_swap_page() calls
	    delete_from_swap_cache().

	    memory.usage/memsw.usage changes to this page/swp_entry will be
	 Case          (A)      (B)       (C)     (D)
         Event
       Before (2)     0/ 1     0/ 1      1/ 1    1/ 1
          ===========================================
          (3)        +1/+1    +1/+1     +1/+1   +1/+1
          (4)          -       0/ 0       -     -1/ 0
          (5)         0/-1     0/ 0     -1/-1    0/ 0
          (6)          -       0/-1       -      0/-1
          ===========================================
       Result         1/ 1     1/ 1      1/ 1    1/ 1

       In any cases, charges to this page should be 1/ 1.

In case of (D), mem_cgroup_try_get_from_swapcache() returns NULL
(because lookup_swap_cgroup() returns NULL), so "+1/+1" at (3) means
charges to the memcg("foo") to which the "current" belongs.
OTOH, "-1/0" at (4) and "0/-1" at (6) means uncharges from the memcg("baa")
to which the page has been charged.

So, if the "foo" and "baa" is different(for example because of task move),
this charge will be moved from "baa" to "foo".

I think this is an unexpected behavior.

This patch fixes this by modifying mem_cgroup_try_get_from_swapcache()
to return the memcg to which the swapcache has been charged if PCG_USED bit
is set.
IIUC, checking PCG_USED bit of swapcache is safe under page lock.

Signed-off-by: Daisuke Nishimura 
Cc: Balbir Singh 
Cc: KAMEZAWA Hiroyuki 
Cc: Li Zefan 
Cc: Hugh Dickins 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

memcg: remove mem_cgroup_calc_mapped_ratio()

2009-04-03T02:04:55+00:00

Currently, mem_cgroup_calc_mapped_ratio() is unused at all.  it can be
removed and KAMEZAWA-san suggested it.

Signed-off-by: KOSAKI Motohiro 
Cc: KAMEZAWA Hiroyuki 
Acked-by: Balbir Singh 
Cc: Johannes Weiner 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

memcg: show memcg information during OOM

2009-04-03T02:04:55+00:00

Add RSS and swap to OOM output from memcg

Display memcg values like failcnt, usage and limit when an OOM occurs due
to memcg.

Thanks to Johannes Weiner, Li Zefan, David Rientjes, Kamezawa Hiroyuki,
Daisuke Nishimura and KOSAKI Motohiro for review.

Sample output
-------------

Task in /a/x killed as a result of limit of /a
memory: usage 1048576kB, limit 1048576kB, failcnt 4183
memory+swap: usage 1400964kB, limit 9007199254740991kB, failcnt 0

[akpm@linux-foundation.org: compilation fix]
[akpm@linux-foundation.org: fix kerneldoc and whitespace]
[akpm@linux-foundation.org: add printk facility level]
Signed-off-by: Balbir Singh 
Cc: KAMEZAWA Hiroyuki 
Cc: Daisuke Nishimura 
Cc: Li Zefan 
Cc: Paul Menage 
Cc: David Rientjes 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds