From 112bc2e120a94a511858918d6866a4978f9c500e Mon Sep 17 00:00:00 2001 From: "Kirill A. Shutemov" Date: Wed, 24 Nov 2010 12:56:58 -0800 Subject: [PATCH] memcg: fix false positive VM_BUG on non-SMP Fix this: kernel BUG at mm/memcontrol.c:2155! invalid opcode: 0000 [#1] last sysfs file: Pid: 18, comm: sh Not tainted 2.6.37-rc3 #3 /Bochs EIP: 0060:[] EFLAGS: 00000246 CPU: 0 EIP is at mem_cgroup_move_account+0xe2/0xf0 EAX: 00000004 EBX: c6f931d4 ECX: c681c300 EDX: c681c000 ESI: c681c300 EDI: ffffffea EBP: c681c000 ESP: c46f3e30 DS: 007b ES: 007b FS: 0000 GS: 0033 SS: 0068 Process sh (pid: 18, ti=c46f2000 task=c6826e60 task.ti=c46f2000) Stack: 00000155 c681c000 0805f000 c46ee180 c46f3e5c c7058820 c1074d37 00000000 08060000 c46db9a0 c46ec080 c7058820 0805f000 08060000 c46f3e98 c1074c50 c106c75e c46f3e98 c46ec080 08060000 0805ffff c46db9a0 c46f3e98 c46e0340 Call Trace: [] ? mem_cgroup_move_charge_pte_range+0xe7/0x130 [] ? mem_cgroup_move_charge_pte_range+0x0/0x130 [] ? walk_page_range+0xee/0x1d0 [] ? mem_cgroup_move_task+0x66/0x90 [] ? mem_cgroup_move_charge_pte_range+0x0/0x130 [] ? mem_cgroup_move_task+0x0/0x90 [] ? cgroup_attach_task+0x136/0x200 [] ? cgroup_tasks_write+0x48/0xc0 [] ? cgroup_file_write+0xde/0x220 [] ? do_page_fault+0x17d/0x3f0 [] ? alloc_fd+0x2d/0xd0 [] ? cgroup_file_write+0x0/0x220 [] ? vfs_write+0x92/0xc0 [] ? sys_write+0x41/0x70 [] ? syscall_call+0x7/0xb Code: 03 00 74 09 8b 44 24 04 e8 1c f1 ff ff 89 73 04 8d 86 b0 00 00 00 b9 01 00 00 00 89 da 31 ff e8 65 f5 ff ff e9 4d ff ff ff 0f 0b <0f> 0b 0f 0b 0f 0b 90 8d b4 26 00 00 00 00 83 ec 10 8b 0d f4 e3 EIP: [] mem_cgroup_move_account+0xe2/0xf0 SS:ESP 0068:c46f3e30 ---[ end trace 7daa1582159b6532 ]--- lock_page_cgroup and unlock_page_cgroup are implemented using bit_spinlock. bit_spinlock doesn't touch the bit if we are on non-SMP machine, so we can't use the bit to check whether the lock was taken. Let's introduce is_page_cgroup_locked based on bit_spin_is_locked instead of PageCgroupLocked to fix it. [akpm@linux-foundation.org: s/is_page_cgroup_locked/page_is_cgroup_locked/] Signed-off-by: Kirill A. Shutemov Reviewed-by: Johannes Weiner Acked-by: KAMEZAWA Hiroyuki Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- include/linux/page_cgroup.h | 7 +++++-- mm/memcontrol.c | 2 +- 2 files changed, 6 insertions(+), 3 deletions(-) diff --git a/include/linux/page_cgroup.h b/include/linux/page_cgroup.h index 5bb13b3db84d..b02195dfc1b0 100644 --- a/include/linux/page_cgroup.h +++ b/include/linux/page_cgroup.h @@ -59,8 +59,6 @@ static inline void ClearPageCgroup##uname(struct page_cgroup *pc) \ static inline int TestClearPageCgroup##uname(struct page_cgroup *pc) \ { return test_and_clear_bit(PCG_##lname, &pc->flags); } -TESTPCGFLAG(Locked, LOCK) - /* Cache flag is set only once (at allocation) */ TESTPCGFLAG(Cache, CACHE) CLEARPCGFLAG(Cache, CACHE) @@ -104,6 +102,11 @@ static inline void unlock_page_cgroup(struct page_cgroup *pc) bit_spin_unlock(PCG_LOCK, &pc->flags); } +static inline int page_is_cgroup_locked(struct page_cgroup *pc) +{ + return bit_spin_is_locked(PCG_LOCK, &pc->flags); +} + #else /* CONFIG_CGROUP_MEM_RES_CTLR */ struct page_cgroup; diff --git a/mm/memcontrol.c b/mm/memcontrol.c index 2efa8ea07ff7..62d1880f6992 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -2152,7 +2152,7 @@ static void __mem_cgroup_move_account(struct page_cgroup *pc, { VM_BUG_ON(from == to); VM_BUG_ON(PageLRU(pc->page)); - VM_BUG_ON(!PageCgroupLocked(pc)); + VM_BUG_ON(!page_is_cgroup_locked(pc)); VM_BUG_ON(!PageCgroupUsed(pc)); VM_BUG_ON(pc->mem_cgroup != from); -- 2.34.1