2012/7/5 Rabin Vincent rabin@rab.in:
From 8a94126eb3aa2824866405fb78bb0b8316f8fd00 Mon Sep 17 00:00:00 2001 From: Rabin Vincent rabin@rab.in Date: Thu, 5 Jul 2012 15:52:23 +0530 Subject: [PATCH] mm: cma: don't replace lowmem pages with highmem
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)
Fix this by replacing only highmem pages with highmem.
Reported-by: Laura Abbott lauraa@codeaurora.org Signed-off-by: Rabin Vincent rabin@rab.in
Acked-by: Michal Nazarewicz mina86@mina86.com
mm/page_alloc.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-)
diff --git a/mm/page_alloc.c b/mm/page_alloc.c index 4403009..4a4f921 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -5635,7 +5635,12 @@ static struct page * __alloc_contig_migrate_alloc(struct page *page, unsigned long private, int **resultp) {
return alloc_page(GFP_HIGHUSER_MOVABLE);
gfp_t gfp_mask = GFP_USER | __GFP_MOVABLE;if (PageHighMem(page))gfp_mask |= __GFP_HIGHMEM;return alloc_page(gfp_mask);}
/* [start, end) must belong to a single zone. */