Messages in this thread | | | From | Kevin Hilman <> | Subject | Re: [PATCH v2] mm, compaction: properly signal and act upon lock and need_sched() contention | Date | Fri, 23 May 2014 08:07:06 -0700 |
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Vlastimil Babka <vbabka@suse.cz> writes:
> On 05/23/2014 04:48 AM, Shawn Guo wrote: >> On 23 May 2014 07:49, Kevin Hilman <khilman@linaro.org> wrote: >>> On Fri, May 16, 2014 at 2:47 AM, Vlastimil Babka <vbabka@suse.cz> wrote: >>>> Compaction uses compact_checklock_irqsave() function to periodically check for >>>> lock contention and need_resched() to either abort async compaction, or to >>>> free the lock, schedule and retake the lock. When aborting, cc->contended is >>>> set to signal the contended state to the caller. Two problems have been >>>> identified in this mechanism. >>> >>> This patch (or later version) has hit next-20140522 (in the form >>> commit 645ceea9331bfd851bc21eea456dda27862a10f4) and according to my >>> bisect, appears to be the culprit of several boot failures on ARM >>> platforms. >> >> On i.MX6 where CMA is enabled, the commit causes the drivers calling >> dma_alloc_coherent() fail to probe. Tracing it a little bit, it seems >> dma_alloc_from_contiguous() always return page as NULL after this >> commit. >> >> Shawn >> > > Really sorry, guys :/ > > -----8<----- > From: Vlastimil Babka <vbabka@suse.cz> > Date: Fri, 23 May 2014 10:18:56 +0200 > Subject: mm-compaction-properly-signal-and-act-upon-lock-and-need_sched-contention-fix2 > > Step 1: Change function name and comment between v1 and v2 so that the return > value signals the opposite thing. > Step 2: Change the call sites to reflect the opposite return value. > Step 3: ??? > Step 4: Make a complete fool of yourself. > Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
Tested-by: Kevin Hilman <khilman@linaro.org>
I verified that this fixes the boot failures I've seen on ARM (i.MX6 and Marvell Armada 370).
Thanks for the quick fix.
Kevin
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