This is a note to let you know that I've just added the patch titled f2fs: compress: fix potential deadlock to the 5.11-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: f2fs-compress-fix-potential-deadlock.patch and it can be found in the queue-5.11 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. commit a4c0253c6fd4d0c2e1b0323dd1ec7d3e68ad22a5 Author: Chao Yu <chao@xxxxxxxxxx> Date: Mon Jan 11 17:42:53 2021 +0800 f2fs: compress: fix potential deadlock [ Upstream commit 3afae09ffea5e08f523823be99a784675995d6bb ] generic/269 reports a hangtask issue, the root cause is ABBA deadlock described as below: Thread A Thread B - down_write(&sbi->gc_lock) -- A - f2fs_write_data_pages - lock all pages in cluster -- B - f2fs_write_multi_pages - f2fs_write_raw_pages - f2fs_write_single_data_page - f2fs_balance_fs - down_write(&sbi->gc_lock) -- A - f2fs_gc - do_garbage_collect - ra_data_block - pagecache_get_page -- B To fix this, it needs to avoid calling f2fs_balance_fs() if there is still cluster pages been locked in context of cluster writeback, so instead, let's call f2fs_balance_fs() in the end of f2fs_write_raw_pages() when all cluster pages were unlocked. Fixes: 4c8ff7095bef ("f2fs: support data compression") Signed-off-by: Chao Yu <yuchao0@xxxxxxxxxx> Signed-off-by: Jaegeuk Kim <jaegeuk@xxxxxxxxxx> Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx> diff --git a/fs/f2fs/compress.c b/fs/f2fs/compress.c index 4bcbacfe33259..7a774c9e4cb89 100644 --- a/fs/f2fs/compress.c +++ b/fs/f2fs/compress.c @@ -1415,7 +1415,7 @@ static int f2fs_write_raw_pages(struct compress_ctx *cc, ret = f2fs_write_single_data_page(cc->rpages[i], &_submitted, NULL, NULL, wbc, io_type, - compr_blocks); + compr_blocks, false); if (ret) { if (ret == AOP_WRITEPAGE_ACTIVATE) { unlock_page(cc->rpages[i]); @@ -1450,6 +1450,9 @@ static int f2fs_write_raw_pages(struct compress_ctx *cc, *submitted += _submitted; } + + f2fs_balance_fs(F2FS_M_SB(mapping), true); + return 0; out_err: for (++i; i < cc->cluster_size; i++) { diff --git a/fs/f2fs/data.c b/fs/f2fs/data.c index aa34d620bec98..d72c99d9bd1f4 100644 --- a/fs/f2fs/data.c +++ b/fs/f2fs/data.c @@ -2743,7 +2743,8 @@ int f2fs_write_single_data_page(struct page *page, int *submitted, sector_t *last_block, struct writeback_control *wbc, enum iostat_type io_type, - int compr_blocks) + int compr_blocks, + bool allow_balance) { struct inode *inode = page->mapping->host; struct f2fs_sb_info *sbi = F2FS_I_SB(inode); @@ -2881,7 +2882,7 @@ int f2fs_write_single_data_page(struct page *page, int *submitted, } unlock_page(page); if (!S_ISDIR(inode->i_mode) && !IS_NOQUOTA(inode) && - !F2FS_I(inode)->cp_task) + !F2FS_I(inode)->cp_task && allow_balance) f2fs_balance_fs(sbi, need_balance_fs); if (unlikely(f2fs_cp_error(sbi))) { @@ -2928,7 +2929,7 @@ static int f2fs_write_data_page(struct page *page, #endif return f2fs_write_single_data_page(page, NULL, NULL, NULL, - wbc, FS_DATA_IO, 0); + wbc, FS_DATA_IO, 0, true); } /* @@ -3096,7 +3097,8 @@ static int f2fs_write_cache_pages(struct address_space *mapping, } #endif ret = f2fs_write_single_data_page(page, &submitted, - &bio, &last_block, wbc, io_type, 0); + &bio, &last_block, wbc, io_type, + 0, true); if (ret == AOP_WRITEPAGE_ACTIVATE) unlock_page(page); #ifdef CONFIG_F2FS_FS_COMPRESSION diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h index bb11759191dcc..1578402c58444 100644 --- a/fs/f2fs/f2fs.h +++ b/fs/f2fs/f2fs.h @@ -3469,7 +3469,7 @@ int f2fs_write_single_data_page(struct page *page, int *submitted, struct bio **bio, sector_t *last_block, struct writeback_control *wbc, enum iostat_type io_type, - int compr_blocks); + int compr_blocks, bool allow_balance); void f2fs_invalidate_page(struct page *page, unsigned int offset, unsigned int length); int f2fs_release_page(struct page *page, gfp_t wait);