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| author | Zhihao Cheng <chengzhihao1@huawei.com> | 2020-01-11 17:50:36 +0800 |
|---|---|---|
| committer | Richard Weinberger <richard@nod.at> | 2020-01-16 23:36:07 +0100 |
| commit | f5de5b83303e61b1f3fb09bd77ce3ac2d7a475f2 (patch) | |
| tree | 68814c2a8259179142c513f41eefa91f0b40e918 | |
| parent | edec51374bce779f37fc209a228139c55d90ec8d (diff) | |
| download | linux-f5de5b83303e61b1f3fb09bd77ce3ac2d7a475f2.tar.bz2 | |
ubifs: Fix deadlock in concurrent bulk-read and writepage
In ubifs, concurrent execution of writepage and bulk read on the same file
may cause ABBA deadlock, for example (Reproduce method see Link):
Process A(Bulk-read starts from page4) Process B(write page4 back)
vfs_read wb_workfn or fsync
... ...
generic_file_buffered_read write_cache_pages
ubifs_readpage LOCK(page4)
ubifs_bulk_read ubifs_writepage
LOCK(ui->ui_mutex) ubifs_write_inode
ubifs_do_bulk_read LOCK(ui->ui_mutex)
find_or_create_page(alloc page4) ↑
LOCK(page4) <-- ABBA deadlock occurs!
In order to ensure the serialization execution of bulk read, we can't
remove the big lock 'ui->ui_mutex' in ubifs_bulk_read(). Instead, we
allow ubifs_do_bulk_read() to lock page failed by replacing
find_or_create_page(FGP_LOCK) with
pagecache_get_page(FGP_LOCK | FGP_NOWAIT).
Signed-off-by: Zhihao Cheng <chengzhihao1@huawei.com>
Suggested-by: zhangyi (F) <yi.zhang@huawei.com>
Cc: <Stable@vger.kernel.org>
Fixes: 4793e7c5e1c ("UBIFS: add bulk-read facility")
Link: https://bugzilla.kernel.org/show_bug.cgi?id=206153
Signed-off-by: Richard Weinberger <richard@nod.at>
| -rw-r--r-- | fs/ubifs/file.c | 4 |
1 files changed, 3 insertions, 1 deletions
diff --git a/fs/ubifs/file.c b/fs/ubifs/file.c index cd52585c8f4f..c649048fcc81 100644 --- a/fs/ubifs/file.c +++ b/fs/ubifs/file.c @@ -786,7 +786,9 @@ static int ubifs_do_bulk_read(struct ubifs_info *c, struct bu_info *bu, if (page_offset > end_index) break; - page = find_or_create_page(mapping, page_offset, ra_gfp_mask); + page = pagecache_get_page(mapping, page_offset, + FGP_LOCK|FGP_ACCESSED|FGP_CREAT|FGP_NOWAIT, + ra_gfp_mask); if (!page) break; if (!PageUptodate(page)) |