diff options
| author | Naoya Horiguchi | 2010-11-24 12:57:13 -0800 |
|---|---|---|
| committer | Linus Torvalds | 2010-11-25 06:50:46 +0900 |
| commit | ea251c1d5c481cda1cf6b0c9e4965f04a6cf2ffc (patch) | |
| tree | 989753f439461fb333432761b8bf39d408572c62 | |
| parent | 5f0af70a25593a9d53b87bc8d31902fb7cc63e40 (diff) | |
pagemap: set pagemap walk limit to PMD boundary
Currently one pagemap_read() call walks in PAGEMAP_WALK_SIZE bytes (== 512
pages.) But there is a corner case where walk_pmd_range() accidentally
runs over a VMA associated with a hugetlbfs file.
For example, when a process has mappings to VMAs as shown below:
# cat /proc/<pid>/maps
...
3a58f6d000-3a58f72000 rw-p 00000000 00:00 0
7fbd51853000-7fbd51855000 rw-p 00000000 00:00 0
7fbd5186c000-7fbd5186e000 rw-p 00000000 00:00 0
7fbd51a00000-7fbd51c00000 rw-s 00000000 00:12 8614 /hugepages/test
then pagemap_read() goes into walk_pmd_range() path and walks in the range
0x7fbd51853000-0x7fbd51a53000, but the hugetlbfs VMA should be handled by
walk_hugetlb_range(). Otherwise PMD for the hugepage is considered bad
and cleared, which causes undesirable results.
This patch fixes it by separating pagemap walk range into one PMD.
Signed-off-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: Jun'ichi Nomura <j-nomura@ce.jp.nec.com>
Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Matt Mackall <mpm@selenic.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
| -rw-r--r-- | fs/proc/task_mmu.c | 3 |
1 files changed, 2 insertions, 1 deletions
diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c index da6b01d70f01..c126c83b9a45 100644 --- a/fs/proc/task_mmu.c +++ b/fs/proc/task_mmu.c @@ -706,6 +706,7 @@ static int pagemap_hugetlb_range(pte_t *pte, unsigned long hmask, * skip over unmapped regions. */ #define PAGEMAP_WALK_SIZE (PMD_SIZE) +#define PAGEMAP_WALK_MASK (PMD_MASK) static ssize_t pagemap_read(struct file *file, char __user *buf, size_t count, loff_t *ppos) { @@ -776,7 +777,7 @@ static ssize_t pagemap_read(struct file *file, char __user *buf, unsigned long end; pm.pos = 0; - end = start_vaddr + PAGEMAP_WALK_SIZE; + end = (start_vaddr + PAGEMAP_WALK_SIZE) & PAGEMAP_WALK_MASK; /* overflow ? */ if (end < start_vaddr || end > end_vaddr) end = end_vaddr; |