This is a note to let you know that I've just added the patch titled btrfs: do not BUG_ON() on ENOMEM when dropping extent items for a range to the 6.0-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: btrfs-do-not-bug_on-on-enomem-when-dropping-extent-items-for-a-range.patch and it can be found in the queue-6.0 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. >From 162d053e15fe985f754ef495a96eb3db970c43ed Mon Sep 17 00:00:00 2001 From: Filipe Manana <fdmanana@xxxxxxxx> Date: Mon, 28 Nov 2022 15:07:30 +0000 Subject: btrfs: do not BUG_ON() on ENOMEM when dropping extent items for a range From: Filipe Manana <fdmanana@xxxxxxxx> commit 162d053e15fe985f754ef495a96eb3db970c43ed upstream. If we get -ENOMEM while dropping file extent items in a given range, at btrfs_drop_extents(), due to failure to allocate memory when attempting to increment the reference count for an extent or drop the reference count, we handle it with a BUG_ON(). This is excessive, instead we can simply abort the transaction and return the error to the caller. In fact most callers of btrfs_drop_extents(), directly or indirectly, already abort the transaction if btrfs_drop_extents() returns any error. Also, we already have error paths at btrfs_drop_extents() that may return -ENOMEM and in those cases we abort the transaction, like for example anything that changes the b+tree may return -ENOMEM due to a failure to allocate a new extent buffer when COWing an existing extent buffer, such as a call to btrfs_duplicate_item() for example. So replace the BUG_ON() calls with proper logic to abort the transaction and return the error. Reported-by: syzbot+0b1fb6b0108c27419f9f@xxxxxxxxxxxxxxxxxxxxxxxxx Link: https://lore.kernel.org/linux-btrfs/00000000000089773e05ee4b9cb4@xxxxxxxxxx/ CC: stable@xxxxxxxxxxxxxxx # 5.4+ Reviewed-by: Josef Bacik <josef@xxxxxxxxxxxxxx> Signed-off-by: Filipe Manana <fdmanana@xxxxxxxx> Reviewed-by: David Sterba <dsterba@xxxxxxxx> Signed-off-by: David Sterba <dsterba@xxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- fs/btrfs/file.c | 10 ++++++++-- 1 file changed, 8 insertions(+), 2 deletions(-) --- a/fs/btrfs/file.c +++ b/fs/btrfs/file.c @@ -880,7 +880,10 @@ next_slot: args->start - extent_offset, 0, false); ret = btrfs_inc_extent_ref(trans, &ref); - BUG_ON(ret); /* -ENOMEM */ + if (ret) { + btrfs_abort_transaction(trans, ret); + break; + } } key.offset = args->start; } @@ -967,7 +970,10 @@ delete_extent_item: key.offset - extent_offset, 0, false); ret = btrfs_free_extent(trans, &ref); - BUG_ON(ret); /* -ENOMEM */ + if (ret) { + btrfs_abort_transaction(trans, ret); + break; + } args->bytes_found += extent_end - key.offset; } Patches currently in stable-queue which might be from fdmanana@xxxxxxxx are queue-6.0/btrfs-do-not-bug_on-on-enomem-when-dropping-extent-items-for-a-range.patch