Messages in this thread | | | Date | Fri, 23 May 2014 10:48:29 +0800 | Subject | Re: [PATCH v2] mm, compaction: properly signal and act upon lock and need_sched() contention | From | Shawn Guo <> |
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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
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