On Wed, Oct 26, 2011 at 12:10 AM, David Rientjes <rientjes@xxxxxxxxxx> wrote: > On Tue, 25 Oct 2011, Colin Cross wrote: > >> > gfp_allowed_mask is initialized to GFP_BOOT_MASK to start so that __GFP_FS >> > is never allowed before the slab allocator is completely initialized, so >> > you've now implicitly made all early boot allocations to be __GFP_NORETRY >> > even though they may not pass it. >> >> Only before interrupts are enabled, and then isn't it vulnerable to >> the same livelock? Interrupts are off, single cpu, kswapd can't run. >> If an allocation ever failed, which seems unlikely, why would retrying >> help? >> > > If you want to claim gfp_allowed_mask as a pm-only entity, then I see no > problem with this approach. However, if gfp_allowed_mask would be allowed > to temporarily change after init for another purpose then it would make > sense to retry because another allocation with __GFP_FS on another cpu or > kswapd could start making progress could allow for future memory freeing. > > The suggestion to add a hook directly into a pm-interface was so that we > could isolate it only to suspend and, to me, is the most maintainable > solution. > pm_restrict_gfp_mask seems to claim gfp_allowed_mask as owned by pm at runtime: "gfp_allowed_mask also should only be modified with pm_mutex held, unless the suspend/hibernate code is guaranteed not to run in parallel with that modification" I think we've wrapped around to Mel's original patch, which adds a pm_suspending() helper that is implemented next to pm_restrict_gfp_mask. His patch puts the check inside !did_some_progress instead of should_alloc_retry, which I prefer as it at least keeps trying until reclaim isn't working. Pekka was trying to avoid adding pm-specific checks into the allocator, which is why I stuck to the symptom (__GFP_FS is clear) rather than the cause (PM). -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: <a href