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Date: Sun, 22 Jun 2008 17:07:23 +0200 From: Peter Zijlstra <peterz@...radead.org> To: Ryan Hope <rmh3093@...il.com> Cc: Nick Piggin <nickpiggin@...oo.com.au>, linux-mm@...r.kernel.org, LKML <linux-kernel@...r.kernel.org> Subject: Re: [BUG] Lockless patches cause hardlock under heavy IO On Sun, 2008-06-22 at 10:37 -0400, Ryan Hope wrote: > Well I couldn't stop playing with this... I am pretty sure the cause > of the hardlocks is in the second half of the patches (the speculative > page ref patches). I reversed all of those patches so that just the > GUP patchs were included and no more hardlocks... then I applied the > concurrent page cache patches from the -rt branch include 1 OLD > speculative page ref patch and this caused hardlocks for peopel again. > However enabling heap randomization fixed the hardlocks for one of the > users and the disabling swap fixed the issue of the other user. I hope > this helps. What are people doing to make it hang? > On Thu, Jun 19, 2008 at 4:19 AM, Nick Piggin <nickpiggin@...oo.com.au> wrote: > > On Thursday 19 June 2008 18:12, Peter Zijlstra wrote: > >> On Wed, 2008-06-18 at 17:15 -0400, Ryan Hope wrote: > >> > I applied the following patches from 2.6-26-rc5-mm3 to 2.6.26-rc6 and > >> > they caused a hardlock under heavy IO: > >> > >> What kind of machine, how much memory, how many spindles, what > >> filesystem and what is heavy load? > >> > >> Furthermore, try the NMI watchdog with serial/net-console to capture its > >> output. > > > > > > Good suggestions. A trace would be really helpful. > > > > As Arjan suggested, debug options especially CONFIG_DEBUG_VM would be > > a good idea to turn on if you haven't already. > > > > BTW. what was the reason for applying those patches? Did you hit the > > problem with -mm also, and hope to narrow it down? > > > > > >> > x86-implement-pte_special.patch > >> > mm-introduce-get_user_pages_fast.patch > >> > mm-introduce-get_user_pages_fast-fix.patch > >> > mm-introduce-get_user_pages_fast-checkpatch-fixes.patch > >> > x86-lockless-get_user_pages_fast.patch > >> > x86-lockless-get_user_pages_fast-checkpatch-fixes.patch > >> > x86-lockless-get_user_pages_fast-fix.patch > >> > x86-lockless-get_user_pages_fast-fix-2.patch > >> > x86-lockless-get_user_pages_fast-fix-2-fix-fix.patch > >> > x86-lockless-get_user_pages_fast-fix-warning.patch > >> > dio-use-get_user_pages_fast.patch > >> > splice-use-get_user_pages_fast.patch > >> > x86-support-1gb-hugepages-with-get_user_pages_lockless.patch > >> > # > >> > mm-readahead-scan-lockless.patch > >> > radix-tree-add-gang_lookup_slot-gang_lookup_slot_tag.patch > >> > #mm-speculative-page-references.patch: clameter saw bustage > >> > mm-speculative-page-references.patch > >> > mm-speculative-page-references-fix.patch > >> > mm-speculative-page-references-fix-fix.patch > >> > mm-speculative-page-references-hugh-fix3.patch > >> > mm-lockless-pagecache.patch > >> > mm-spinlock-tree_lock.patch > >> > powerpc-implement-pte_special.patch > >> > > >> > I am on an x86_64. I dont know what other info you need... > > > > Can you isolate it to one of the two groups of patches? I suspect it > > might be the latter so you might try that first -- this version of > > speculative page references is very nice in theory but it is a little > > more complex to implement the slowpaths so it could be an error there. > > -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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