On 05/23/2014 02:34 AM, Vlastimil Babka wrote: > On 05/23/2014 04:48 AM, Shawn Guo wrote: >> On 23 May 2014 07:49, Kevin Hilman <[email protected]> wrote: >>> On Fri, May 16, 2014 at 2:47 AM, Vlastimil Babka <[email protected]> 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 <[email protected]> > 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.
Tested-by: Stephen Warren <[email protected]> This fix doesn't seem to be in linux-next yet:-( -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
