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oom: extract panic helper function

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There are various points in the oom killer where the kernel must determine
whether to panic or not.  It's better to extract this to a helper function
to remove all the confusion as to its semantics.

Also fix a call to dump_header() where tasklist_lock is not read- locked,
as required.

There's no functional change with this patch.

Acked-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Signed-off-by: David Rientjes <rientjes@google.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
David Rientjes 2010-08-09 17:18:54 -07:00 • committed by Linus Torvalds
commit 309ed88250
2 changed files with 30 additions and 24 deletions
Download patch file Download diff file Expand all files Collapse all files

1
include/linux/oom.h
View file

@ -22,6 +22,7 @@ enum oom_constraint {
CONSTRAINT_NONE,
CONSTRAINT_CPUSET,
CONSTRAINT_MEMORY_POLICY,
CONSTRAINT_MEMCG,
};
extern int try_set_zone_oom(struct zonelist *zonelist, gfp_t gfp_flags);

53
mm/oom_kill.c
View file

@ -521,17 +521,40 @@ static int oom_kill_process(struct task_struct *p, gfp_t gfp_mask, int order,
return oom_kill_task(victim);
}
/*
* Determines whether the kernel must panic because of the panic_on_oom sysctl.
*/
static void check_panic_on_oom(enum oom_constraint constraint, gfp_t gfp_mask,
int order)
{
if (likely(!sysctl_panic_on_oom))
return;
if (sysctl_panic_on_oom != 2) {
/*
* panic_on_oom == 1 only affects CONSTRAINT_NONE, the kernel
* does not panic for cpuset, mempolicy, or memcg allocation
* failures.
*/
if (constraint != CONSTRAINT_NONE)
return;
}
read_lock(&tasklist_lock);
dump_header(NULL, gfp_mask, order, NULL);
read_unlock(&tasklist_lock);
panic("Out of memory: %s panic_on_oom is enabled\n",
sysctl_panic_on_oom == 2 ? "compulsory" : "system-wide");
}
#ifdef CONFIG_CGROUP_MEM_RES_CTLR
void mem_cgroup_out_of_memory(struct mem_cgroup *mem, gfp_t gfp_mask)
{
unsigned long points = 0;
struct task_struct *p;
if (sysctl_panic_on_oom == 2)
panic("out of memory(memcg). panic_on_oom is selected.\n");
check_panic_on_oom(CONSTRAINT_MEMCG, gfp_mask, 0);
read_lock(&tasklist_lock);
retry:
p = select_bad_process(&points, mem, CONSTRAINT_NONE, NULL);
p = select_bad_process(&points, mem, CONSTRAINT_MEMCG, NULL);
if (!p || PTR_ERR(p) == -1UL)
goto out;
@ -632,8 +655,8 @@ retry:
/* Found nothing?!?! Either we hang forever, or we panic. */
if (!p) {
read_unlock(&tasklist_lock);
dump_header(NULL, gfp_mask, order, NULL);
read_unlock(&tasklist_lock);
panic("Out of memory and no killable processes...\n");
}
@ -655,9 +678,7 @@ void pagefault_out_of_memory(void)
/* Got some memory back in the last second. */
return;
if (sysctl_panic_on_oom)
panic("out of memory from page fault. panic_on_oom is selected.\n");
check_panic_on_oom(CONSTRAINT_NONE, 0, 0);
read_lock(&tasklist_lock);
/* unknown gfp_mask and order */
__out_of_memory(0, 0, CONSTRAINT_NONE, NULL);
@ -704,29 +725,13 @@ void out_of_memory(struct zonelist *zonelist, gfp_t gfp_mask,
return;
}
if (sysctl_panic_on_oom == 2) {
dump_header(NULL, gfp_mask, order, NULL);
panic("out of memory. Compulsory panic_on_oom is selected.\n");
}
/*
* Check if there were limitations on the allocation (only relevant for
* NUMA) that may require different handling.
*/
constraint = constrained_alloc(zonelist, gfp_mask, nodemask);
check_panic_on_oom(constraint, gfp_mask, order);
read_lock(&tasklist_lock);
if (unlikely(sysctl_panic_on_oom)) {
/*
* panic_on_oom only affects CONSTRAINT_NONE, the kernel
* should not panic for cpuset or mempolicy induced memory
* failures.
*/
if (constraint == CONSTRAINT_NONE) {
dump_header(NULL, gfp_mask, order, NULL);
read_unlock(&tasklist_lock);
panic("Out of memory: panic_on_oom is enabled\n");
}
}
__out_of_memory(gfp_mask, order, constraint, nodemask);
read_unlock(&tasklist_lock);