Messages in this thread | | | Date | Tue, 24 Jun 2008 09:12:51 -0700 | From | "Paul E. McKenney" <> | Subject | Re: [BUG] Lockless patches cause hardlock under heavy IO |
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On Tue, Jun 24, 2008 at 11:57:05AM -0400, Ryan Hope wrote: > I can give you a list of patches that should correspond to the thread > name (for the most part): > > fix-double-unlock_page-in-2626-rc5-mm3-kernel-bug-at-mm-filemapc-575.patch > > fix_munlock-page-table-walk.patch > > migration_entry_wait-fix.patch > > PATCH collect lru meminfo statistics from correct offset > > Mlocked field of /proc/meminfo display silly number. > because trivial mistake exist in meminfo_read_proc(). > > You can also look in our git repo to see the code that changed with > these patches if you cant track them down in LKML: > http://zen-sources.org/cgi-bin/gitweb.cgi?p=kernel-mm.git;a=shortlog;h=refs/heads/lkml
Thank you! And is this using Classic RCU or Preemptable RCU?
Thanx, Paul
> On Tue, Jun 24, 2008 at 11:32 AM, Paul E. McKenney > <paulmck@linux.vnet.ibm.com> wrote: > > On Tue, Jun 24, 2008 at 11:12:03AM -0400, Ryan Hope wrote: > >> Well i tried to run pure -mm this weekend, it locked as soon as I got > >> into gnome so I applied a couple of the bug fixes from lkml and -mm > >> seems to be running stable now. I cant seem to get it to hard lock > >> now, at least not doing the simple stuff that was causing it to hard > >> lock on my other patchset, either the lockless patches expose some bug > >> that in -rc6 or lockless requires some other patches further up in the > >> -mm series file. > > > > Cool!!! Any guess as to which of the bug fixes did the trick? > > Failing that, a list of the bug fixes that you applied? > > > > Thanx, Paul > > > >> On Mon, Jun 23, 2008 at 8:13 PM, Nick Piggin <nickpiggin@yahoo.com.au> wrote: > >> > On Monday 23 June 2008 23:05, Paul E. McKenney wrote: > >> >> On Mon, Jun 23, 2008 at 09:54:52PM +1000, Nick Piggin wrote: > >> >> > On Monday 23 June 2008 13:51, Ryan Hope wrote: > >> >> > > well i get the hardlock on -mm with out using reiser4, i am pretty > >> >> > > sure is swap related > >> >> > > >> >> > The guys seeing hangs don't use PREEMPT_RCU, do they? > >> >> > > >> >> > In my swapping tests, I found -mm3 to be stable with classic RCU, but > >> >> > on a hunch, I tried PREEMPT_RCU and it crashed a couple of times rather > >> >> > quickly. First crash was in find_get_pages so I suspected lockless > >> >> > pagecache doing something subtly wrong with the RCU API, but I just got > >> >> > another crash in __d_lookup: > >> >> > >> >> Could you please send me a repeat-by? (At least Alexey is no longer > >> >> alone!) > >> > > >> > OK, I had DEBUG_PAGEALLOC in the .config, which I think is probably > >> > important to reproduce it (but the fact that I'm reproducing oopses > >> > with << PAGE_SIZE objects like dentries and radix tree nodes indicates > >> > that there is even more free-before-grace activity going undetected -- > >> > if you construct a test case using full pages, it might become even > >> > easier to detect with DEBUG_PAGEALLOC). > >> > > >> > 2 socket, 8 core x86 system. > >> > > >> > I mounted two tmpfs filesystems, one contains a single large file > >> > which is formatted as 1K block size ext3 and mounted loopback, the > >> > other is used directly. Linux kernel source is unpacked on each mount > >> > and concurrent make -j128 on each. This pushes it pretty hard into > >> > swap. Classic RCU survived another 5 hours of this last night. > >> > > >> > But that's a fairly convoluted test for an RCU problem. I expect it > >> > should be easier to trigger with something more targetted... > >> > > >
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