On Thu, Jul 03, 2014 at 12:54:36PM -0700, Hugh Dickins wrote: > On Wed, 2 Jul 2014, Hugh Dickins wrote: > > On Wed, 2 Jul 2014, Johannes Weiner wrote: > > > > > > Could you give the following patch a spin? I put it in the mmots > > > stack on top of mm-memcontrol-rewrite-charge-api-fix-shmem_unuse-fix. > > > > I'm just with the laptop until this evening. I slapped it on top of > > my 3.16-rc2-mm1 plus fixes (but obviously minus my memcg_batch one > > - which incidentally continues to run without crashing on the G5), > > and it quickly gave me this lockdep splat, which doesn't look very > > different from the one before. > > > > I see there's now an -rc3-mm1, I'll try it out on that in half an > > hour... but unless I send word otherwise, assume that's the same. > > Yes, I get that lockdep report each time on -rc3-mm1 + your patch. There are two instances where I missed to make &rtpz->lock IRQ-safe: diff --git a/mm/memcontrol.c b/mm/memcontrol.c index 91b621846e10..bbaa3f4cf4db 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -3919,7 +3919,7 @@ unsigned long mem_cgroup_soft_limit_reclaim(struct zone *zone, int order, gfp_mask, &nr_scanned); nr_reclaimed += reclaimed; *total_scanned += nr_scanned; - spin_lock(&mctz->lock); + spin_lock_irq(&mctz->lock); /* * If we failed to reclaim anything from this memory cgroup @@ -3959,7 +3959,7 @@ unsigned long mem_cgroup_soft_limit_reclaim(struct zone *zone, int order, */ /* If excess == 0, no tree ops */ __mem_cgroup_insert_exceeded(mz, mctz, excess); - spin_unlock(&mctz->lock); + spin_unlock_irq(&mctz->lock); css_put(&mz->memcg->css); loop++; /* That should make it complete - but the IRQ toggling costs are fairly high so I'm rewriting the batching code to use the page lists that most uncharges have anyway, and then batch the no-IRQ sections. > I also twice got a flurry of res_counter.c:28 underflow warnings. > Hmm, 62 of them each time (I was checking for a number near 512, > which would suggest a THP/4k confusion, but no). The majority > of them coming from mem_cgroup_reparent_charges. I haven't seen these yet. But the location makes sense: if there are any imbalances they'll be noticed during a group's final uncharges. > But the laptop stayed up fine (for two hours before I had to stop > it), and the G5 has run fine with that load for 16 hours now, no > problems with release_pages, and not even a res_counter.c:28 (but > I don't use lockdep on it). Great! > The x86 workstation ran fine for 4.5 hours, then hit some deadlock > which I doubt had any connection to your changes: looked more like > a jbd2 transaction was failing to complete (which, with me trying > ext4 on loop on tmpfs, might be more my problem than anyone else's). > > Oh, but nearly forgot, I did an earlier run on the laptop last night, > which crashed within minutes on > > VM_BUG_ON_PAGE(!(pc->flags & PCG_MEM)) > mm/memcontrol.c:6680! > page had count 1 mapcount 0 mapping anon index 0x196 > flags locked uptodate reclaim swapbacked, pcflags 1, memcg not root > mem_cgroup_migrate < move_to_new_page < migrate_pages < compact_zone < > compact_zone_order < try_to_compact_pages < __alloc_pages_direct_compact < > __alloc_pages_nodemask < alloc_pages_vma < do_huge_pmd_anonymous_page < > handle_mm_fault < __do_page_fault Haven't seen that one yet, either. The only way I can see this happen is when the same page gets selected for migration twice in a row. Maybe a race with putback, where it gets added to the LRU but isolated by compaction before putback drops the refcount - will verify that. Thanks for your reports! -- 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/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>