From 309ed882508cc471320ff79265e7340774d6746c Mon Sep 17 00:00:00 2001 From: David Rientjes Date: Mon, 9 Aug 2010 17:18:54 -0700 Subject: [PATCH] oom: extract panic helper function 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 Signed-off-by: David Rientjes Cc: KAMEZAWA Hiroyuki Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- include/linux/oom.h | 1 + mm/oom_kill.c | 53 +++++++++++++++++++++++++-------------------- 2 files changed, 30 insertions(+), 24 deletions(-) diff --git a/include/linux/oom.h b/include/linux/oom.h index 53766231562..3ae6d94d054 100644 --- a/include/linux/oom.h +++ b/include/linux/oom.h @@ -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); diff --git a/mm/oom_kill.c b/mm/oom_kill.c index 01b5e01e52c..fca886d8b5f 100644 --- a/mm/oom_kill.c +++ b/mm/oom_kill.c @@ -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); -- 2.20.1