oom: default to killing current for pagefault ooms The pagefault oom handler does not know the context (gfp_mask, order, etc) in which memory was not found when a VM_FAULT_OOM is generated. The only information known is that current is trying to allocate in that context, so killing it is a legitimate response (and is the default for architectures that do not even use the pagefault oom handler such as ia64 and powerpc). When a VM_FAULT_OOM occurs, the pagefault oom handler will now attempt to kill current by default. If it is unkillable, the oom killer is called to find a memory-hogging task to kill instead that will lead to future memory freeing. Signed-off-by: David Rientjes --- mm/oom_kill.c | 18 +++++++++++++----- 1 files changed, 13 insertions(+), 5 deletions(-) diff --git a/mm/oom_kill.c b/mm/oom_kill.c --- a/mm/oom_kill.c +++ b/mm/oom_kill.c @@ -711,15 +711,23 @@ void out_of_memory(struct zonelist *zonelist, gfp_t gfp_mask, } /* - * The pagefault handler calls here because it is out of memory, so kill a - * memory-hogging task. If a populated zone has ZONE_OOM_LOCKED set, a parallel - * oom killing is already in progress so do nothing. If a task is found with - * TIF_MEMDIE set, it has been killed so do nothing and allow it to exit. + * The pagefault handler calls here because it is out of memory, so kill current + * by default. If it's unkillable, then fallback to killing a memory-hogging + * task. If a populated zone has ZONE_OOM_LOCKED set, a parallel oom killing is + * already in progress so do nothing. If a task is found with TIF_MEMDIE set, + * it has been killed so do nothing and allow it to exit. */ void pagefault_out_of_memory(void) { + unsigned long totalpages; + int err; + if (try_set_system_oom()) { - out_of_memory(NULL, 0, 0, NULL); + constrained_alloc(NULL, 0, NULL, &totalpages); + err = oom_kill_process(current, 0, 0, 0, totalpages, NULL, + "Out of memory (pagefault)"); + if (err) + out_of_memory(NULL, 0, 0, NULL); clear_system_oom(); } if (!test_thread_flag(TIF_MEMDIE))