From 6a6dccba2fdc2a69f1f36b8f1c0acc8598e7221b Mon Sep 17 00:00:00 2001 From: Rabin Vincent 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: [] (ext4_getblk+0x0/0x180) from [] (ext4_bread+0x1c/0x98) [] (ext4_bread+0x0/0x98) from [] (ext4_mkdir+0x160/0x3bc) r4:c15337f0 [] (ext4_mkdir+0x0/0x3bc) from [] (vfs_mkdir+0x8c/0x98) [] (vfs_mkdir+0x0/0x98) from [] (sys_mkdirat+0x74/0xac) r6:00000000 r5:c152eb40 r4:000001ff r3:c14b43f0 [] (sys_mkdirat+0x0/0xac) from [] (sys_mkdir+0x20/0x24) r6:beccdcf0 r5:00074000 r4:beccdbbc [] (sys_mkdir+0x0/0x24) from [] (ret_fast_syscall+0x0/0x30) Fix this by replacing only highmem pages with highmem. Reported-by: Laura Abbott Signed-off-by: Rabin Vincent Acked-by: Michal Nazarewicz Signed-off-by: Marek Szyprowski --- 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 44030096da631b..4a4f9219683f63 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. */