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authorJohannes Weiner <hannes@cmpxchg.org>2013-09-12 15:13:36 -0700
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2014-11-21 09:22:55 -0800
commit20c92c01bfe0d5046f16853c07e2a24ea463cdf2 (patch)
tree5f9a2d40648e52bd0398865adf738bb1b5ac62ce
parentb13a714fb4e374d9e23185d6f47e86109909cfe8 (diff)
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arch: mm: remove obsolete init OOM protection
commit 94bce453c78996cc4373d5da6cfabe07fcc6d9f9 upstream. The memcg code can trap tasks in the context of the failing allocation until an OOM situation is resolved. They can hold all kinds of locks (fs, mm) at this point, which makes it prone to deadlocking. This series converts memcg OOM handling into a two step process that is started in the charge context, but any waiting is done after the fault stack is fully unwound. Patches 1-4 prepare architecture handlers to support the new memcg requirements, but in doing so they also remove old cruft and unify out-of-memory behavior across architectures. Patch 5 disables the memcg OOM handling for syscalls, readahead, kernel faults, because they can gracefully unwind the stack with -ENOMEM. OOM handling is restricted to user triggered faults that have no other option. Patch 6 reworks memcg's hierarchical OOM locking to make it a little more obvious wth is going on in there: reduce locked regions, rename locking functions, reorder and document. Patch 7 implements the two-part OOM handling such that tasks are never trapped with the full charge stack in an OOM situation. This patch: Back before smart OOM killing, when faulting tasks were killed directly on allocation failures, the arch-specific fault handlers needed special protection for the init process. Now that all fault handlers call into the generic OOM killer (see commit 609838cfed97: "mm: invoke oom-killer from remaining unconverted page fault handlers"), which already provides init protection, the arch-specific leftovers can be removed. Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Reviewed-by: Michal Hocko <mhocko@suse.cz> Acked-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: David Rientjes <rientjes@google.com> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: azurIt <azurit@pobox.sk> Acked-by: Vineet Gupta <vgupta@synopsys.com> [arch/arc bits] Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Cong Wang <xiyou.wangcong@gmail.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
-rw-r--r--arch/arc/mm/fault.c5
-rw-r--r--arch/score/mm/fault.c6
-rw-r--r--arch/tile/mm/fault.c6
3 files changed, 0 insertions, 17 deletions
diff --git a/arch/arc/mm/fault.c b/arch/arc/mm/fault.c
index 0902d399b6c9..87f4281a4b64 100644
--- a/arch/arc/mm/fault.c
+++ b/arch/arc/mm/fault.c
@@ -120,7 +120,6 @@ good_area:
goto bad_area;
}
-survive:
/*
* If for any reason at all we couldn't handle the fault,
* make sure we exit gracefully rather than endlessly redo
@@ -200,10 +199,6 @@ no_context:
die("Oops", regs, address, cause_code);
out_of_memory:
- if (is_global_init(tsk)) {
- yield();
- goto survive;
- }
up_read(&mm->mmap_sem);
if (user_mode(regs)) {
diff --git a/arch/score/mm/fault.c b/arch/score/mm/fault.c
index 6b18fb0189ae..4b71a626d41e 100644
--- a/arch/score/mm/fault.c
+++ b/arch/score/mm/fault.c
@@ -100,7 +100,6 @@ good_area:
goto bad_area;
}
-survive:
/*
* If for any reason at all we couldn't handle the fault,
* make sure we exit gracefully rather than endlessly redo
@@ -167,11 +166,6 @@ no_context:
*/
out_of_memory:
up_read(&mm->mmap_sem);
- if (is_global_init(tsk)) {
- yield();
- down_read(&mm->mmap_sem);
- goto survive;
- }
if (!user_mode(regs))
goto no_context;
pagefault_out_of_memory();
diff --git a/arch/tile/mm/fault.c b/arch/tile/mm/fault.c
index f7f99f90cbe0..ac553eed6390 100644
--- a/arch/tile/mm/fault.c
+++ b/arch/tile/mm/fault.c
@@ -430,7 +430,6 @@ good_area:
goto bad_area;
}
- survive:
/*
* If for any reason at all we couldn't handle the fault,
* make sure we exit gracefully rather than endlessly redo
@@ -568,11 +567,6 @@ no_context:
*/
out_of_memory:
up_read(&mm->mmap_sem);
- if (is_global_init(tsk)) {
- yield();
- down_read(&mm->mmap_sem);
- goto survive;
- }
if (is_kernel_mode)
goto no_context;
pagefault_out_of_memory();