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authorShijie Luo <luoshijie1@huawei.com>2020-11-02 04:07:40 +0300
committerLinus Torvalds <torvalds@linux-foundation.org>2020-11-02 23:14:19 +0300
commit3f08842098e842c51e3b97d0dcdebf810b32558e (patch)
treea1b568a08112ffb7898d89e8bbf3d7fc36715bfd /mm
parent58b999d7a22c59313e1e84832607c7a61640f4e7 (diff)
downloadlinux-3f08842098e842c51e3b97d0dcdebf810b32558e.tar.xz
mm: mempolicy: fix potential pte_unmap_unlock pte error
When flags in queue_pages_pte_range don't have MPOL_MF_MOVE or MPOL_MF_MOVE_ALL bits, code breaks and passing origin pte - 1 to pte_unmap_unlock seems like not a good idea. queue_pages_pte_range can run in MPOL_MF_MOVE_ALL mode which doesn't migrate misplaced pages but returns with EIO when encountering such a page. Since commit a7f40cfe3b7a ("mm: mempolicy: make mbind() return -EIO when MPOL_MF_STRICT is specified") and early break on the first pte in the range results in pte_unmap_unlock on an underflow pte. This can lead to lockups later on when somebody tries to lock the pte resp. page_table_lock again.. Fixes: a7f40cfe3b7a ("mm: mempolicy: make mbind() return -EIO when MPOL_MF_STRICT is specified") Signed-off-by: Shijie Luo <luoshijie1@huawei.com> Signed-off-by: Miaohe Lin <linmiaohe@huawei.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Oscar Salvador <osalvador@suse.de> Acked-by: Michal Hocko <mhocko@suse.com> Cc: Miaohe Lin <linmiaohe@huawei.com> Cc: Feilong Lin <linfeilong@huawei.com> Cc: Shijie Luo <luoshijie1@huawei.com> Cc: <stable@vger.kernel.org> Link: https://lkml.kernel.org/r/20201019074853.50856-1-luoshijie1@huawei.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm')
-rw-r--r--mm/mempolicy.c6
1 files changed, 3 insertions, 3 deletions
diff --git a/mm/mempolicy.c b/mm/mempolicy.c
index 3fde772ef5ef..3ca4898f3f24 100644
--- a/mm/mempolicy.c
+++ b/mm/mempolicy.c
@@ -525,7 +525,7 @@ static int queue_pages_pte_range(pmd_t *pmd, unsigned long addr,
unsigned long flags = qp->flags;
int ret;
bool has_unmovable = false;
- pte_t *pte;
+ pte_t *pte, *mapped_pte;
spinlock_t *ptl;
ptl = pmd_trans_huge_lock(pmd, vma);
@@ -539,7 +539,7 @@ static int queue_pages_pte_range(pmd_t *pmd, unsigned long addr,
if (pmd_trans_unstable(pmd))
return 0;
- pte = pte_offset_map_lock(walk->mm, pmd, addr, &ptl);
+ mapped_pte = pte = pte_offset_map_lock(walk->mm, pmd, addr, &ptl);
for (; addr != end; pte++, addr += PAGE_SIZE) {
if (!pte_present(*pte))
continue;
@@ -571,7 +571,7 @@ static int queue_pages_pte_range(pmd_t *pmd, unsigned long addr,
} else
break;
}
- pte_unmap_unlock(pte - 1, ptl);
+ pte_unmap_unlock(mapped_pte, ptl);
cond_resched();
if (has_unmovable)