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authorMinchan Kim <minchan@kernel.org>2012-10-08 16:32:54 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2012-10-09 16:22:52 +0900
commit74c08f982674cfd5dfeb2702d631db9bcdabf788 (patch)
tree6645d574ecd7fb5e7509a3cfda95605d8cfeb7f5 /mm
parent723a0644a7255f532575fd43245f9ef976491328 (diff)
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memory-hotplug: don't replace lowmem pages with highmem
The changelog for commit 6a6dccba2fdc ("mm: cma: don't replace lowmem pages with highmem") mentioned that lowmem pages can be replaced by highmem pages during CMA migration. 6a6dccba2fdc fixed that issue. Quote from that changelog: : The filesystem layer expects pages in the block device's mapping to not : be in highmem (the mapping's gfp mask is set in bdget()), but CMA can : currently replace lowmem pages with highmem pages, leading to crashes in : filesystem code such as the one below: : : Unable to handle kernel NULL pointer dereference at virtual address 00000400 : pgd = c0c98000 : [00000400] *pgd=00c91831, *pte=00000000, *ppte=00000000 : Internal error: Oops: 817 [#1] PREEMPT SMP ARM : CPU: 0 Not tainted (3.5.0-rc5+ #80) : PC is at __memzero+0x24/0x80 : ... : Process fsstress (pid: 323, stack limit = 0xc0cbc2f0) : Backtrace: : [<c010e3f0>] (ext4_getblk+0x0/0x180) from [<c010e58c>] (ext4_bread+0x1c/0x98) : [<c010e570>] (ext4_bread+0x0/0x98) from [<c0117944>] (ext4_mkdir+0x160/0x3bc) : r4:c15337f0 : [<c01177e4>] (ext4_mkdir+0x0/0x3bc) from [<c00c29e0>] (vfs_mkdir+0x8c/0x98) : [<c00c2954>] (vfs_mkdir+0x0/0x98) from [<c00c2a60>] (sys_mkdirat+0x74/0xac) : r6:00000000 r5:c152eb40 r4:000001ff r3:c14b43f0 : [<c00c29ec>] (sys_mkdirat+0x0/0xac) from [<c00c2ab8>] (sys_mkdir+0x20/0x24) : r6:beccdcf0 r5:00074000 r4:beccdbbc : [<c00c2a98>] (sys_mkdir+0x0/0x24) from [<c000e3c0>] (ret_fast_syscall+0x0/0x30) Memory-hotplug has same problem as CMA has so the same fix can be applied to memory-hotplug as well. Fix it by reusing. Signed-off-by: Minchan Kim <minchan@kernel.org> Cc: Kamezawa Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Reviewed-by: Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com> Acked-by: Michal Nazarewicz <mina86@mina86.com> Cc: Marek Szyprowski <m.szyprowski@samsung.com> Cc: Wen Congyang <wency@cn.fujitsu.com> Acked-by: David Rientjes <rientjes@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm')
-rw-r--r--mm/memory_hotplug.c15
1 files changed, 6 insertions, 9 deletions
diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
index b35016156c19..f9ac0955e10a 100644
--- a/mm/memory_hotplug.c
+++ b/mm/memory_hotplug.c
@@ -756,13 +756,6 @@ static unsigned long scan_lru_pages(unsigned long start, unsigned long end)
return 0;
}
-static struct page *
-hotremove_migrate_alloc(struct page *page, unsigned long private, int **x)
-{
- /* This should be improooooved!! */
- return alloc_page(GFP_HIGHUSER_MOVABLE);
-}
-
#define NR_OFFLINE_AT_ONCE_PAGES (256)
static int
do_migrate_range(unsigned long start_pfn, unsigned long end_pfn)
@@ -813,8 +806,12 @@ do_migrate_range(unsigned long start_pfn, unsigned long end_pfn)
putback_lru_pages(&source);
goto out;
}
- /* this function returns # of failed pages */
- ret = migrate_pages(&source, hotremove_migrate_alloc, 0,
+
+ /*
+ * alloc_migrate_target should be improooooved!!
+ * migrate_pages returns # of failed pages.
+ */
+ ret = migrate_pages(&source, alloc_migrate_target, 0,
true, MIGRATE_SYNC);
if (ret)
putback_lru_pages(&source);