Re: [BUG] Lockless patches cause hardlock under heavy IO

["Ryan Hope" <rmh3093@gmail.com>]

Well if there are no more suggestion we are going to have to abandon
testing lockless for now because it is causing hardlocks on everyones
box who uses it. I hope the next round of patches has better luck.

On Thu, Jun 19, 2008 at 4:19 AM, Nick Piggin <nickpiggin@yahoo.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.
>