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mm/shmem: fix shmem_swapin() race with swapoff
[ Upstream commit2efa33fc7f
] When I was investigating the swap code, I found the below possible race window: CPU 1 CPU 2 ----- ----- shmem_swapin swap_cluster_readahead if (likely(si->flags & (SWP_BLKDEV | SWP_FS_OPS))) { swapoff .. si->swap_file = NULL; .. struct inode *inode = si->swap_file->f_mapping->host;[oops!] Close this race window by using get/put_swap_device() to guard against concurrent swapoff. Link: https://lkml.kernel.org/r/20210426123316.806267-5-linmiaohe@huawei.com Fixes:8fd2e0b505
("mm: swap: check if swap backing device is congested or not") Signed-off-by: Miaohe Lin <linmiaohe@huawei.com> Reviewed-by: "Huang, Ying" <ying.huang@intel.com> Cc: Dennis Zhou <dennis@kernel.org> Cc: Tim Chen <tim.c.chen@linux.intel.com> Cc: Hugh Dickins <hughd@google.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@suse.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Alex Shi <alexs@kernel.org> Cc: Matthew Wilcox <willy@infradead.org> Cc: Minchan Kim <minchan@kernel.org> Cc: Wei Yang <richard.weiyang@gmail.com> Cc: Yang Shi <shy828301@gmail.com> Cc: David Hildenbrand <david@redhat.com> Cc: Yu Zhao <yuzhao@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Sasha Levin <sashal@kernel.org>
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parent
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commit
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1 changed files with 13 additions and 1 deletions
14
mm/shmem.c
14
mm/shmem.c
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@ -1698,7 +1698,8 @@ static int shmem_swapin_page(struct inode *inode, pgoff_t index,
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struct address_space *mapping = inode->i_mapping;
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struct shmem_inode_info *info = SHMEM_I(inode);
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struct mm_struct *charge_mm = vma ? vma->vm_mm : current->mm;
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struct page *page;
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struct swap_info_struct *si;
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struct page *page = NULL;
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swp_entry_t swap;
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int error;
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@ -1706,6 +1707,12 @@ static int shmem_swapin_page(struct inode *inode, pgoff_t index,
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swap = radix_to_swp_entry(*pagep);
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*pagep = NULL;
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/* Prevent swapoff from happening to us. */
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si = get_swap_device(swap);
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if (!si) {
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error = EINVAL;
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goto failed;
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}
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/* Look it up and read it in.. */
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page = lookup_swap_cache(swap, NULL, 0);
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if (!page) {
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@ -1767,6 +1774,8 @@ static int shmem_swapin_page(struct inode *inode, pgoff_t index,
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swap_free(swap);
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*pagep = page;
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if (si)
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put_swap_device(si);
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return 0;
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failed:
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if (!shmem_confirm_swap(mapping, index, swap))
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@ -1777,6 +1786,9 @@ static int shmem_swapin_page(struct inode *inode, pgoff_t index,
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put_page(page);
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}
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if (si)
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put_swap_device(si);
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return error;
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}
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