From: Yangtao Li frank.li@vivo.com
[ Upstream commit babedcbac164cec970872b8097401ca913a80e61 ]
BUG_ON() will be triggered when writing files concurrently, because the same page is writtenback multiple times.
1597 void folio_end_writeback(struct folio *folio) 1598 { ...... 1618 if (!__folio_end_writeback(folio)) 1619 BUG(); ...... 1625 }
kernel BUG at mm/filemap.c:1619! Call Trace: <TASK> f2fs_write_end_io+0x1a0/0x370 blk_update_request+0x6c/0x410 blk_mq_end_request+0x15/0x130 blk_complete_reqs+0x3c/0x50 __do_softirq+0xb8/0x29b ? sort_range+0x20/0x20 run_ksoftirqd+0x19/0x20 smpboot_thread_fn+0x10b/0x1d0 kthread+0xde/0x110 ? kthread_complete_and_exit+0x20/0x20 ret_from_fork+0x22/0x30 </TASK>
Below is the concurrency scenario:
[Process A] [Process B] [Process C] f2fs_write_raw_pages() - redirty_page_for_writepage() - unlock page() f2fs_do_write_data_page() - lock_page() - clear_page_dirty_for_io() - set_page_writeback() [1st writeback] ..... - unlock page()
generic_perform_write() - f2fs_write_begin() - wait_for_stable_page()
- f2fs_write_end() - set_page_dirty()
- lock_page() - f2fs_do_write_data_page() - set_page_writeback() [2st writeback]
This problem was introduced by the previous commit 7377e853967b ("f2fs: compress: fix potential deadlock of compress file"). All pagelocks were released in f2fs_write_raw_pages(), but whether the page was in the writeback state was ignored in the subsequent writing process. Let's fix it by waiting for the page to writeback before writing.
Cc: Christoph Hellwig hch@lst.de Fixes: 4c8ff7095bef ("f2fs: support data compression") Fixes: 7377e853967b ("f2fs: compress: fix potential deadlock of compress file") Signed-off-by: Qi Han hanqi@vivo.com Signed-off-by: Yangtao Li frank.li@vivo.com Reviewed-by: Chao Yu chao@kernel.org Signed-off-by: Jaegeuk Kim jaegeuk@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org --- fs/f2fs/compress.c | 6 ++++++ 1 file changed, 6 insertions(+)
diff --git a/fs/f2fs/compress.c b/fs/f2fs/compress.c index 4fa62f98cb515..455fac164fda0 100644 --- a/fs/f2fs/compress.c +++ b/fs/f2fs/compress.c @@ -1477,6 +1477,12 @@ static int f2fs_write_raw_pages(struct compress_ctx *cc, if (!PageDirty(cc->rpages[i])) goto continue_unlock;
+ if (PageWriteback(cc->rpages[i])) { + if (wbc->sync_mode == WB_SYNC_NONE) + goto continue_unlock; + f2fs_wait_on_page_writeback(cc->rpages[i], DATA, true, true); + } + if (!clear_page_dirty_for_io(cc->rpages[i])) goto continue_unlock;