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author | Miao Xie <miaox@cn.fujitsu.com> | 2010-05-24 14:32:08 -0700 |
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committer | Linus Torvalds <torvalds@linux-foundation.org> | 2010-05-25 08:06:57 -0700 |
commit | c0ff7453bb5c7c98e0885fb94279f2571946f280 (patch) | |
tree | 8bb2b169a5145f0496575dbd2f48bb4b1c83f819 /include/linux/cpuset.h | |
parent | 708c1bbc9d0c3e57f40501794d9b0eed29d10fce (diff) | |
download | kernel_samsung_espresso10-c0ff7453bb5c7c98e0885fb94279f2571946f280.zip kernel_samsung_espresso10-c0ff7453bb5c7c98e0885fb94279f2571946f280.tar.gz kernel_samsung_espresso10-c0ff7453bb5c7c98e0885fb94279f2571946f280.tar.bz2 |
cpuset,mm: fix no node to alloc memory when changing cpuset's mems
Before applying this patch, cpuset updates task->mems_allowed and
mempolicy by setting all new bits in the nodemask first, and clearing all
old unallowed bits later. But in the way, the allocator may find that
there is no node to alloc memory.
The reason is that cpuset rebinds the task's mempolicy, it cleans the
nodes which the allocater can alloc pages on, for example:
(mpol: mempolicy)
task1 task1's mpol task2
alloc page 1
alloc on node0? NO 1
1 change mems from 1 to 0
1 rebind task1's mpol
0-1 set new bits
0 clear disallowed bits
alloc on node1? NO 0
...
can't alloc page
goto oom
This patch fixes this problem by expanding the nodes range first(set newly
allowed bits) and shrink it lazily(clear newly disallowed bits). So we
use a variable to tell the write-side task that read-side task is reading
nodemask, and the write-side task clears newly disallowed nodes after
read-side task ends the current memory allocation.
[akpm@linux-foundation.org: fix spello]
Signed-off-by: Miao Xie <miaox@cn.fujitsu.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Nick Piggin <npiggin@suse.de>
Cc: Paul Menage <menage@google.com>
Cc: Lee Schermerhorn <lee.schermerhorn@hp.com>
Cc: Hugh Dickins <hugh.dickins@tiscali.co.uk>
Cc: Ravikiran Thirumalai <kiran@scalex86.org>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Christoph Lameter <cl@linux-foundation.org>
Cc: Andi Kleen <andi@firstfloor.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'include/linux/cpuset.h')
-rw-r--r-- | include/linux/cpuset.h | 43 |
1 files changed, 43 insertions, 0 deletions
diff --git a/include/linux/cpuset.h b/include/linux/cpuset.h index a73454a..20b51ca 100644 --- a/include/linux/cpuset.h +++ b/include/linux/cpuset.h @@ -86,9 +86,44 @@ extern void rebuild_sched_domains(void); extern void cpuset_print_task_mems_allowed(struct task_struct *p); +/* + * reading current mems_allowed and mempolicy in the fastpath must protected + * by get_mems_allowed() + */ +static inline void get_mems_allowed(void) +{ + current->mems_allowed_change_disable++; + + /* + * ensure that reading mems_allowed and mempolicy happens after the + * update of ->mems_allowed_change_disable. + * + * the write-side task finds ->mems_allowed_change_disable is not 0, + * and knows the read-side task is reading mems_allowed or mempolicy, + * so it will clear old bits lazily. + */ + smp_mb(); +} + +static inline void put_mems_allowed(void) +{ + /* + * ensure that reading mems_allowed and mempolicy before reducing + * mems_allowed_change_disable. + * + * the write-side task will know that the read-side task is still + * reading mems_allowed or mempolicy, don't clears old bits in the + * nodemask. + */ + smp_mb(); + --ACCESS_ONCE(current->mems_allowed_change_disable); +} + static inline void set_mems_allowed(nodemask_t nodemask) { + task_lock(current); current->mems_allowed = nodemask; + task_unlock(current); } #else /* !CONFIG_CPUSETS */ @@ -187,6 +222,14 @@ static inline void set_mems_allowed(nodemask_t nodemask) { } +static inline void get_mems_allowed(void) +{ +} + +static inline void put_mems_allowed(void) +{ +} + #endif /* !CONFIG_CPUSETS */ #endif /* _LINUX_CPUSET_H */ |