The patch titled
memcg: fix false positive VM_BUG on non-SMP
has been added to the -mm tree. Its filename is
memcg-fix-false-positive-vm_bug-on-non-smp.patch
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*** Remember to use Documentation/SubmitChecklist when testing your code ***
See http://userweb.kernel.org/~akpm/stuff/added-to-mm.txt to find
out what to do about this
The current -mm tree may be found at http://userweb.kernel.org/~akpm/mmotm/
------------------------------------------------------
Subject: memcg: fix false positive VM_BUG on non-SMP
From: Kirill A. Shutemov <kirill@xxxxxxxxxxxxx>
------------[ cut here ]------------
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:[<c10731b2>] 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:
[<c1074d37>] ? mem_cgroup_move_charge_pte_range+0xe7/0x130
[<c1074c50>] ? mem_cgroup_move_charge_pte_range+0x0/0x130
[<c106c75e>] ? walk_page_range+0xee/0x1d0
[<c10725d6>] ? mem_cgroup_move_task+0x66/0x90
[<c1074c50>] ? mem_cgroup_move_charge_pte_range+0x0/0x130
[<c1072570>] ? mem_cgroup_move_task+0x0/0x90
[<c1042616>] ? cgroup_attach_task+0x136/0x200
[<c1042878>] ? cgroup_tasks_write+0x48/0xc0
[<c1041e9e>] ? cgroup_file_write+0xde/0x220
[<c101398d>] ? do_page_fault+0x17d/0x3f0
[<c108a79d>] ? alloc_fd+0x2d/0xd0
[<c1041dc0>] ? cgroup_file_write+0x0/0x220
[<c1077ba2>] ? vfs_write+0x92/0xc0
[<c1077c81>] ? sys_write+0x41/0x70
[<c1140e3d>] ? 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: [<c10731b2>] 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.
Signed-off-by: Kirill A. Shutemov <kirill@xxxxxxxxxxxxx>
Cc: Daisuke Nishimura <nishimura@xxxxxxxxxxxxxxxxx>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@xxxxxxxxxxxxxx>
Cc: Balbir Singh <balbir@xxxxxxxxxxxxxxxxxx>
Cc: <stable@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
include/linux/page_cgroup.h | 7 +++++--
mm/memcontrol.c | 2 +-
2 files changed, 6 insertions(+), 3 deletions(-)
diff -puN include/linux/page_cgroup.h~memcg-fix-false-positive-vm_bug-on-non-smp include/linux/page_cgroup.h
--- a/include/linux/page_cgroup.h~memcg-fix-false-positive-vm_bug-on-non-smp
+++ a/include/linux/page_cgroup.h
@@ -59,8 +59,6 @@ static inline void ClearPageCgroup##unam
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(st
bit_spin_unlock(PCG_LOCK, &pc->flags);
}
+static inline int is_page_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 -puN mm/memcontrol.c~memcg-fix-false-positive-vm_bug-on-non-smp mm/memcontrol.c
--- a/mm/memcontrol.c~memcg-fix-false-positive-vm_bug-on-non-smp
+++ a/mm/memcontrol.c
@@ -2152,7 +2152,7 @@ static void __mem_cgroup_move_account(st
{
VM_BUG_ON(from == to);
VM_BUG_ON(PageLRU(pc->page));
- VM_BUG_ON(!PageCgroupLocked(pc));
+ VM_BUG_ON(!is_page_cgroup_locked(pc));
VM_BUG_ON(!PageCgroupUsed(pc));
VM_BUG_ON(pc->mem_cgroup != from);
_
Patches currently in -mm which might be from kirill@xxxxxxxxxxxxx are
memcg-fix-false-positive-vm_bug-on-non-smp.patch
linux-next.patch
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