Messages in this thread Patch in this message | | | Date | Mon, 21 May 2007 12:16:26 -0700 | From | Chris Wright <> | Subject | [patch 14/69] oom: fix constraint deadlock |
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-stable review patch. If anyone has any objections, please let us know. ---------------------
From: David Rientjes <rientjes@google.com>
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 <ak@suse.de> Cc: Nick Piggin <npiggin@suse.de> Cc: Christoph Lameter <clameter@engr.sgi.com> Cc: Martin J. Bligh <mbligh@mbligh.org> Signed-off-by: David Rientjes <rientjes@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Chris Wright <chrisw@sous-sol.org> ---
mm/oom_kill.c | 10 ++++++---- 1 file changed, 6 insertions(+), 4 deletions(-)
--- linux-2.6.21.1.orig/mm/oom_kill.c +++ linux-2.6.21.1/mm/oom_kill.c @@ -397,6 +397,7 @@ void out_of_memory(struct zonelist *zone 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) @@ -411,14 +412,15 @@ void out_of_memory(struct zonelist *zone show_mem(); } - 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)"); -- - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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