linux-kernel - Re: [PATCH] Revert "mm/cma: manage the memory of the CMA area by using the ZONE

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Date:   Thu, 17 May 2018 18:49:47 +0200
From:   Michal Hocko <mhocko@...nel.org>
To:     Ville Syrjälä <ville.syrjala@...ux.intel.com>
Cc:     Joonsoo Kim <iamjoonsoo.kim@....com>,
        "Aneesh Kumar K . V" <aneesh.kumar@...ux.vnet.ibm.com>,
        Tony Lindgren <tony@...mide.com>,
        Vlastimil Babka <vbabka@...e.cz>,
        Johannes Weiner <hannes@...xchg.org>,
        Laura Abbott <lauraa@...eaurora.org>,
        Marek Szyprowski <m.szyprowski@...sung.com>,
        Mel Gorman <mgorman@...hsingularity.net>,
        Michal Nazarewicz <mina86@...a86.com>,
        Minchan Kim <minchan@...nel.org>,
        Rik van Riel <riel@...hat.com>,
        Russell King <linux@...linux.org.uk>,
        Will Deacon <will.deacon@....com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        linux-mm@...ck.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] Revert "mm/cma: manage the memory of the CMA area by
 using the ZONE_MOVABLE"

On Thu 17-05-18 16:58:32, Ville Syrjälä wrote:
> On Thu, May 17, 2018 at 04:36:29PM +0300, Ville Syrjälä wrote:
> > On Thu, May 17, 2018 at 03:21:09PM +0200, Michal Hocko wrote:
> > > On Thu 17-05-18 15:59:59, Ville Syrjala wrote:
> > > > From: Ville Syrjälä <ville.syrjala@...ux.intel.com>
> > > > 
> > > > This reverts commit bad8c6c0b1144694ecb0bc5629ede9b8b578b86e.
> > > > 
> > > > Make x86 with HIGHMEM=y and CMA=y boot again.
> > > 
> > > Is there any bug report with some more details? It is much more
> > > preferable to fix the issue rather than to revert the whole thing
> > > right away.
> > 
> > The machine I have in front of me right now didn't give me anything.
> > Black screen, and netconsole was silent. No serial port on this
> > machine unfortunately.
> 
> Booted on another machine with serial:

Could you provide your .config please?

[...]
> [    0.000000] cma: Reserved 4 MiB at 0x0000000037000000
[...]
> [    0.000000] BUG: Bad page state in process swapper  pfn:377fe
> [    0.000000] page:f53effc0 count:0 mapcount:-127 mapping:00000000 index:0x0

OK, so this looks the be the source of the problem. -128 would be a
buddy page but I do not see anything that would set the counter to -127
and the real map count updates shouldn't really happen that early.

Maybe CONFIG_DEBUG_VM and CONFIG_DEBUG_HIGHMEM will tell us more.

> [    0.000000] flags: 0x80000000()
> [    0.000000] raw: 80000000 00000000 00000000 ffffff80 00000000 00000100 00000200 00000001
> [    0.000000] page dumped because: nonzero mapcount
> [    0.000000] Modules linked in:
> [    0.000000] CPU: 0 PID: 0 Comm: swapper Not tainted 4.17.0-rc5-elk+ #145
> [    0.000000] Hardware name: Dell Inc. Latitude E5410/03VXMC, BIOS A15 07/11/2013
> [    0.000000] Call Trace:
> [    0.000000]  dump_stack+0x60/0x96
> [    0.000000]  bad_page+0x9a/0x100
> [    0.000000]  free_pages_check_bad+0x3f/0x60
> [    0.000000]  free_pcppages_bulk+0x29d/0x5b0
> [    0.000000]  free_unref_page_commit+0x84/0xb0
> [    0.000000]  free_unref_page+0x3e/0x70
> [    0.000000]  __free_pages+0x1d/0x20
> [    0.000000]  free_highmem_page+0x19/0x40
> [    0.000000]  add_highpages_with_active_regions+0xab/0xeb
> [    0.000000]  set_highmem_pages_init+0x66/0x73
> [    0.000000]  mem_init+0x1b/0x1d7
> [    0.000000]  start_kernel+0x17a/0x363
> [    0.000000]  i386_start_kernel+0x95/0x99
> [    0.000000]  startup_32_smp+0x164/0x168

-- 
Michal Hocko
SUSE Labs