This is a note to let you know that I've just added the patch titled ext4: avoid allocating blocks from corrupted group in ext4_mb_try_best_found() to the 5.4-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: ext4-avoid-allocating-blocks-from-corrupted-group-in.patch and it can be found in the queue-5.4 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. commit f358d2831a4b6c45acec0c4f4cf1eef8cf2101eb Author: Baokun Li <libaokun1@xxxxxxxxxx> Date: Thu Jan 4 22:20:38 2024 +0800 ext4: avoid allocating blocks from corrupted group in ext4_mb_try_best_found() [ Upstream commit 4530b3660d396a646aad91a787b6ab37cf604b53 ] Determine if the group block bitmap is corrupted before using ac_b_ex in ext4_mb_try_best_found() to avoid allocating blocks from a group with a corrupted block bitmap in the following concurrency and making the situation worse. ext4_mb_regular_allocator ext4_lock_group(sb, group) ext4_mb_good_group // check if the group bbitmap is corrupted ext4_mb_complex_scan_group // Scan group gets ac_b_ex but doesn't use it ext4_unlock_group(sb, group) ext4_mark_group_bitmap_corrupted(group) // The block bitmap was corrupted during // the group unlock gap. ext4_mb_try_best_found ext4_lock_group(ac->ac_sb, group) ext4_mb_use_best_found mb_mark_used // Allocating blocks in block bitmap corrupted group Signed-off-by: Baokun Li <libaokun1@xxxxxxxxxx> Reviewed-by: Jan Kara <jack@xxxxxxx> Link: https://lore.kernel.org/r/20240104142040.2835097-7-libaokun1@xxxxxxxxxx Signed-off-by: Theodore Ts'o <tytso@xxxxxxx> Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx> diff --git a/fs/ext4/mballoc.c b/fs/ext4/mballoc.c index 0745330228cf0..1af9daaff8ba2 100644 --- a/fs/ext4/mballoc.c +++ b/fs/ext4/mballoc.c @@ -1802,6 +1802,9 @@ int ext4_mb_try_best_found(struct ext4_allocation_context *ac, return err; ext4_lock_group(ac->ac_sb, group); + if (unlikely(EXT4_MB_GRP_BBITMAP_CORRUPT(e4b->bd_info))) + goto out; + max = mb_find_extent(e4b, ex.fe_start, ex.fe_len, &ex); if (max > 0) { @@ -1809,6 +1812,7 @@ int ext4_mb_try_best_found(struct ext4_allocation_context *ac, ext4_mb_use_best_found(ac, e4b); } +out: ext4_unlock_group(ac->ac_sb, group); ext4_mb_unload_buddy(e4b);