On Fri, Mar 30, 2018 at 07:34:59PM +0900, Tetsuo Handa wrote:
> Maybe we can make "give up by default upon SIGKILL" and let callers
> explicitly say "do not give up upon SIGKILL".
I really strongly disapprove of this patch. This GFP flag will be abused
like every other GFP flag.
> +++ b/mm/page_alloc.c
> @@ -4183,6 +4183,13 @@ bool gfp_pfmemalloc_allowed(gfp_t gfp_mask)
> if (current->flags & PF_MEMALLOC)
> goto nopage;
>
> + /* Can give up if caller is willing to give up upon fatal signals */
> + if (fatal_signal_pending(current) &&
> + !(gfp_mask & (__GFP_UNKILLABLE | __GFP_NOFAIL))) {
> + gfp_mask |= __GFP_NOWARN;
> + goto nopage;
> + }
> +
> /* Try direct reclaim and then allocating */
This part is superficially tempting, although without the UNKILLABLE. ie:
+ if (fatal_signal_pending(current) && !(gfp_mask & __GFP_NOFAIL)) {
+ gfp_mask |= __GFP_NOWARN;
+ goto nopage;
+ }
It makes some sense to me to prevent tasks with a fatal signal pending
from being able to trigger reclaim. But I'm worried about what memory
allocation failures it might trigger on paths that aren't accustomed to
seeing failures.
