From: Filipe Manana fdmanana@suse.com
commit 2c8507c63f5498d4ee4af404a8e44ceae4345056 upstream.
This commit re-attempts the backport of the change to the linux-5.4.y branch. Commit 3d770d44dd5c ("btrfs: avoid monopolizing a core when activating a swap file") on this branch was reverted.
During swap activation we iterate over the extents of a file and we can have many thousands of them, so we can end up in a busy loop monopolizing a core. Avoid this by doing a voluntary reschedule after processing each extent.
CC: stable@vger.kernel.org # 5.4+ Reviewed-by: Qu Wenruo wqu@suse.com Signed-off-by: Filipe Manana fdmanana@suse.com Signed-off-by: David Sterba dsterba@suse.com Signed-off-by: Koichiro Den koichiro.den@canonical.com --- fs/btrfs/inode.c | 2 ++ 1 file changed, 2 insertions(+)
diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c index cd72409ccc94..004894e6dd23 100644 --- a/fs/btrfs/inode.c +++ b/fs/btrfs/inode.c @@ -11079,6 +11079,8 @@ static int btrfs_swap_activate(struct swap_info_struct *sis, struct file *file, }
start += len; + + cond_resched(); }
if (bsi.block_len)