lkml.org 
[lkml]   [2011]   [Apr]   [13]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [ARM] Issue of memory compaction on kernel 2.6.35.9
On Wed, Apr 13, 2011 at 05:05:33PM +0530, naveen yadav wrote:
> Dear all,
>
> we want to varify compaction on ARM and we are using 2.6.25.9 kernel
> on cortex a9.
>
> Since ARM does not have HUGETLB_PAGE support and compaction is HUGE
> PAGE independent so I removed from config file
>

Bear in mind that if you intend to depend on compaction to allow
devices to use high-order allocations, you could be in trouble in
the future. Compaction gives no guarantees that high-order pages will
be available so a device must still be able to cope with allocation
failure. In the case of transparent hugepage support and hugetlbfs,
allocation failure is not a serious problem.

> ******************************************************************************************************************************
> # support for memory compaction
> config COMPACTION
> bool "Allow for memory compaction"
> select MIGRATION
> #depends on EXPERIMENTAL && HUGETLB_PAGE && MMU
> depends on EXPERIMENTAL && MMU
> help
> Allows the compaction of memory for the allocation of huge pages.
> ******************************************************************************************************************************
> after triggering Memory Compaction by writing any value to
> /proc/sys/vm/compact_memory i am getting the SVC mode crash
> ******************************************************************************************************************************
> #echo 1 > /proc/sys/vm/compact_memory
> Unable to handle kernel paging request at virtual address ee420be4
> pgd = d9c6c000
> [ee420be4] *pgd=00000000
> Internal error: Oops: 805 [#1] PREEMPT
> last sysfs file:
> Modules linked in:
> CPU: 0    Not tainted  (2.6.35.9 #16)
> PC is at compact_zone+0x178/0x610
> LR is at compact_zone+0x138/0x610
> pc : [<c009f30c>]    lr : [<c009f2cc>]    psr: 40000093
> sp : d9d75e40  ip : c0380978  fp : d9d75e94
> r10: d9d74000  r9 : c03806c8  r8 : 00069704
> r7 : 00069800  r6 : 00d2e080  r5 : c04ea080  r4 : d9d75e9c
> r3 : 60000093  r2 : 00000002  r1 : ee420be4  r0 : ee430b82
> Flags: nZcv  IRQs off  FIQs on  Mode SVC_32  ISA ARM  Segment us
> ******************************************************************************************************************************
>
>
> We tried to narrow down the prob... I found crash is form
> ?del_page_from_lru_list(zone, page, page_lru(page)); ? function
> isolate_migratepages
>

ARM punches holes in the mem_map structure to save memory and
memory compaction is not aware of them because it couldn't have been
configured. Debug what PFN is failing and see if it is near a memory
hole. If it's within a memory hole, that's your problem.

--
Mel Gorman
SUSE Labs
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/

\
 
 \ /
  Last update: 2011-04-13 15:55    [W:0.023 / U:4.264 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site