On Thu, Feb 02, 2023 at 11:30:42AM -1000, Tejun Heo wrote:
The bug we're discussing here is that when ext4 writes out a pagecache page in an encrypted file, it first encrypts the data into a bounce page, then passes the bounce page (which don't have a memcg) to wbc_account_cgroup_owner(). Maybe the proper fix is to just pass the pagecache page to wbc_account_cgroup_owner() instead? See below for ext4 (a separate patch would be needed for f2fs):
Yeah, this makes sense to me and is the right thing to do no matter what. wbc_account_cgroup_owner() should be fed the origin page so that the IO can be blamed on the owner of that page.
Thanks. These patches fix this for ext4 and f2fs:
* https://lore.kernel.org/r/20230203005503.141557-1-ebiggers@kernel.org * https://lore.kernel.org/r/20230203010239.216421-1-ebiggers@kernel.org
- Eric