Gitweb:
http://git.kernel.org/git/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=2b45ab3398a0ba119b1f672c7c56fd5a431b7f0a
Commit: 2b45ab3398a0ba119b1f672c7c56fd5a431b7f0a
Parent: 2b744c01a54fe0c9974ff1b29522f25f07084053
Author: David Rientjes <[EMAIL PROTECTED]>
AuthorDate: Sun May 6 14:50:00 2007 -0700
Committer: Linus Torvalds <[EMAIL PROTECTED]>
CommitDate: Mon May 7 12:12:55 2007 -0700
oom: fix constraint deadlock
Fixes a deadlock in the OOM killer for allocations that are not
__GFP_HARDWALL.
Before the OOM killer checks for the allocation constraint, it takes
callback_mutex.
constrained_alloc() iterates through each zone in the allocation zonelist
and calls cpuset_zone_allowed_softwall() to determine whether an allocation
for gfp_mask is possible. If a zone's node is not in the OOM-triggering
task's mems_allowed, it is not exiting, and we did not fail on a
__GFP_HARDWALL allocation, cpuset_zone_allowed_softwall() attempts to take
callback_mutex to check the nearest exclusive ancestor of current's cpuset.
This results in deadlock.
We now take callback_mutex after iterating through the zonelist since we
don't need it yet.
Cc: Andi Kleen <[EMAIL PROTECTED]>
Cc: Nick Piggin <[EMAIL PROTECTED]>
Cc: Christoph Lameter <[EMAIL PROTECTED]>
Cc: Martin J. Bligh <[EMAIL PROTECTED]>
Signed-off-by: David Rientjes <[EMAIL PROTECTED]>
Cc: <[EMAIL PROTECTED]>
Signed-off-by: Andrew Morton <[EMAIL PROTECTED]>
Signed-off-by: Linus Torvalds <[EMAIL PROTECTED]>
---
mm/oom_kill.c | 10 ++++++----
1 files changed, 6 insertions(+), 4 deletions(-)
diff --git a/mm/oom_kill.c b/mm/oom_kill.c
index 038d223..a700141 100644
--- a/mm/oom_kill.c
+++ b/mm/oom_kill.c
@@ -399,6 +399,7 @@ void out_of_memory(struct zonelist *zonelist, gfp_t
gfp_mask, int order)
struct task_struct *p;
unsigned long points = 0;
unsigned long freed = 0;
+ int constraint;
blocking_notifier_call_chain(&oom_notify_list, 0, &freed);
if (freed > 0)
@@ -416,14 +417,15 @@ void out_of_memory(struct zonelist *zonelist, gfp_t
gfp_mask, int order)
if (sysctl_panic_on_oom == 2)
panic("out of memory. Compulsory panic_on_oom is selected.\n");
- cpuset_lock();
- read_lock(&tasklist_lock);
-
/*
* Check if there were limitations on the allocation (only relevant for
* NUMA) that may require different handling.
*/
- switch (constrained_alloc(zonelist, gfp_mask)) {
+ constraint = constrained_alloc(zonelist, gfp_mask);
+ cpuset_lock();
+ read_lock(&tasklist_lock);
+
+ switch (constraint) {
case CONSTRAINT_MEMORY_POLICY:
oom_kill_process(current, points,
"No available memory (MPOL_BIND)");
-
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