The patch titled
bugfix for memory cgroup controller: charge refcnt race fix
has been removed from the -mm tree. Its filename was
bugfix-for-memory-cgroup-controller-charge-refcnt-race-fix.patch
This patch was dropped because it was folded into
memory-controller-add-per-container-lru-and-reclaim-v7.patch
The current -mm tree may be found at http://userweb.kernel.org/~akpm/mmotm/
------------------------------------------------------
Subject: bugfix for memory cgroup controller: charge refcnt race fix
From: KAMEZAWA Hiroyuki <[EMAIL PROTECTED]>
The logic of uncharge is
- decrement refcnt -> lock page cgroup -> remove page cgroup.
But the logic of charging is
- lock page cgroup -> increment refcnt -> return.
Then, one charge will be added to a page_cgroup under being removed.
This makes no big trouble (like panic) but one charge is lost.
This patch add a test at charging to verify page_cgroup's refcnt is
greater than 0. If not, unlock and retry.
Changelog v2->v3
* adjusted to 2.6.23-mm1
Changelog v1->v2:
* added cpu_relax() before retry.
Signed-off-by: KAMEZAWA Hiroyuki <[EMAIL PROTECTED]>
Cc: Pavel Emelianov <[EMAIL PROTECTED]>
Cc: Paul Menage <[EMAIL PROTECTED]>
Cc: Peter Zijlstra <[EMAIL PROTECTED]>
Cc: "Eric W. Biederman" <[EMAIL PROTECTED]>
Cc: Nick Piggin <[EMAIL PROTECTED]>
Cc: Kirill Korotaev <[EMAIL PROTECTED]>
Cc: Herbert Poetzl <[EMAIL PROTECTED]>
Cc: David Rientjes <[EMAIL PROTECTED]>
Cc: Vaidyanathan Srinivasan <[EMAIL PROTECTED]>
Signed-off-by: Andrew Morton <[EMAIL PROTECTED]>
---
mm/memcontrol.c | 10 ++++++++--
1 file changed, 8 insertions(+), 2 deletions(-)
diff -puN
mm/memcontrol.c~bugfix-for-memory-cgroup-controller-charge-refcnt-race-fix
mm/memcontrol.c
--- a/mm/memcontrol.c~bugfix-for-memory-cgroup-controller-charge-refcnt-race-fix
+++ a/mm/memcontrol.c
@@ -281,14 +281,20 @@ int mem_cgroup_charge(struct page *page,
* to see if the cgroup page already has a page_cgroup associated
* with it
*/
+retry:
lock_page_cgroup(page);
pc = page_get_page_cgroup(page);
/*
* The page_cgroup exists and the page has already been accounted
*/
if (pc) {
- atomic_inc(&pc->ref_cnt);
- goto done;
+ if (unlikely(!atomic_inc_not_zero(&pc->ref_cnt))) {
+ /* this page is under being uncharged ? */
+ unlock_page_cgroup(page);
+ cpu_relax();
+ goto retry;
+ } else
+ goto done;
}
unlock_page_cgroup(page);
_
Patches currently in -mm which might be from [EMAIL PROTECTED] are
origin.patch
memcgroup-temporarily-revert-swapoff-mod.patch
memory-controller-add-per-container-lru-and-reclaim-v7.patch
bugfix-for-memory-cgroup-controller-charge-refcnt-race-fix.patch
memory-controller-improve-user-interface.patch
memory-controller-make-charging-gfp-mask-aware.patch
bugfix-for-memory-cgroup-controller-fix-error-handling-path-in-mem_charge_cgroup.patch
bugfix-for-memory-controller-add-helper-function-for-assigning-cgroup-to-page.patch
bugfix-for-memory-cgroup-controller-migration-under-memory-controller-fix.patch
bugfix-for-memory-cgroup-controller-avoid-pagelru-page-in-mem_cgroup_isolate_pages.patch
memory-cgroup-enhancements-fix-zone-handling-in-try_to_free_mem_cgroup_page.patch
memory-cgroup-enhancements-force_empty-interface-for-dropping-all-account-in-empty-cgroup.patch
memory-cgroup-enhancements-remember-a-page-is-charged-as-page-cache.patch
memory-controller-use-rcu_read_lock-in-mem_cgroup_cache_charge.patch
memcgroup-tidy-up-mem_cgroup_charge_common.patch
memcgroup-fix-hang-with-shmem-tmpfs.patch
memory-cgroup-enhancements-remember-a-page-is-on-active-list-of-cgroup-or-not.patch
memory-cgroup-enhancements-add-status-accounting-function-for-memory-cgroup.patch
memory-cgroup-enhancements-add-memorystat-file.patch
memory-cgroup-enhancements-add-pre_destroy-handler.patch
memory-cgroup-enhancements-implicit-force_empty-at-rmdir.patch
per-zone-and-reclaim-enhancements-for-memory-controller-take-3-add-scan_global_lru-macro.patch
per-zone-and-reclaim-enhancements-for-memory-controller-take-3-nid-zid-helper-function-for-cgroup.patch
per-zone-and-reclaim-enhancements-for-memory-controller-take-3-per-zone-active-inactive-counter.patch
per-zone-and-reclaim-enhancements-for-memory-controller-take-3-calculate-mapper_ratio-per-cgroup.patch
per-zone-and-reclaim-enhancements-for-memory-controller-take-3-calculate-active-inactive-imbalance-per-cgroup.patch
per-zone-and-reclaim-enhancements-for-memory-controller-take-3-remember-reclaim-priority-in-memory-cgroup.patch
per-zone-and-reclaim-enhancements-for-memory-controller-take-3-calculate-the-number-of-pages-to-be-scanned-per-cgroup.patch
per-zone-and-reclaim-enhancements-for-memory-controller-take-3-modifies-vmscanc-for-isolate-globa-cgroup-lru-activity.patch
per-zone-and-reclaim-enhancements-for-memory-controller-take-3-per-zone-lru-for-cgroup.patch
per-zone-and-reclaim-enhancements-for-memory-controller-take-3-per-zone-lock-for-cgroup.patch
memory-controller-remove-control_type-feature.patch
update-documentation-controller-memorytxt.patch
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