On Fri, Sep 28, 2012 at 02:43:30PM +0900, Minchan Kim wrote: > On Thu, Sep 27, 2012 at 03:11:59PM -0700, Andrew Morton wrote: > > On Thu, 27 Sep 2012 13:29:11 +0200 > > Thierry Reding <thierry.reding@xxxxxxxxxxxxxxxxx> wrote: > > > > > Hi Marek, > > > > > > any idea why CMA might be broken in next-20120926. I see that there > > > haven't been any major changes to CMA itself, but there's been quite a > > > bit of restructuring of various memory allocation bits lately. I wasn't > > > able to track the problem down, though. > > > > > > What I see is this during boot (with CMA_DEBUG enabled): > > > > > > [ 0.266904] cma: dma_alloc_from_contiguous(cma db474f80, count 64, align 6) > > > [ 0.284469] cma: dma_alloc_from_contiguous(): memory range at c09d7000 is busy, retrying > > > [ 0.293648] cma: dma_alloc_from_contiguous(): memory range at c09d7800 is busy, retrying > > > ... > > > [ 2.648619] DMA: failed to allocate 256 KiB pool for atomic coherent allocation > > > ... > > > [ 4.196193] WARNING: at /home/thierry.reding/src/kernel/linux-ipmp.git/arch/arm/mm/dma-mapping.c:485 __alloc_from_pool+0xdc/0x110() > > > [ 4.207988] coherent pool not initialised! > > > > > > So the pool isn't getting initialized properly because CMA can't get at > > > the memory. Do you have any hints as to what might be going on? If it's > > > any help, I started seeing this with next-20120926 and it is in today's > > > next as well. > > > > > > > Bart and Minchan have made recent changes to CMA. Let us cc them. > > Hi all, > > I have no time now so I look over the problem during short time > so I mighte be wrong. Even I should leave the office soon and > Korea will have long vacation from now on so I will be off by next week. > So it's hard to reach on me. > > I hope this patch fixes the bug. If this patch fixes the problem > but has some problem about description or someone has better idea, > feel free to modify and resend to akpm, Please. > > Thierry, Could you test below patch? > > From 24a547855fa2bd4212a779cc73997837148310b3 Mon Sep 17 00:00:00 2001 > From: Minchan Kim <minchan@xxxxxxxxxx> > Date: Fri, 28 Sep 2012 14:28:32 +0900 > Subject: [PATCH] revert mm: compaction: iron out isolate_freepages_block() > and isolate_freepages_range() > > [1] made bug on CMA. > The nr_scanned should be never equal to total_isolated for successful CMA. > This patch reverts part of the patch. > Why should nr_scanned never be equal to total_isolated for CMA? Reverting the patch reintroduces Andrew's complaint that this function was "straggly" and getting a bit out of control so I'd much prefer to understand why this situation is not true and fix that. -- Mel Gorman SUSE Labs -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>