On Thu, Mar 18, 2021 at 11:55:43AM +0000, Matthew Wilcox wrote:

On Thu, Mar 18, 2021 at 11:29:28AM +0000, Luis Henriques wrote:

quoted

On Thu, Mar 18, 2021 at 02:03:02PM +0300, Kirill A. Shutemov wrote:

quoted

On Thu, Mar 18, 2021 at 11:59:59AM +0100, Miklos Szeredi wrote:

quoted

quoted

[16247.536348] page:00000000dfe36ab1 refcount:673 mapcount:0 mapping:00000000f982a7f8 index:0x1400 pfn:0x4c65e00
[16247.536359] head:00000000dfe36ab1 order:9 compound_mapcount:0 compound_pincount:0

This is a compound page alright.   Have no idea how it got into fuse's
pagecache.

Luis, do you have CONFIG_READ_ONLY_THP_FOR_FS enabled?

Yes, it looks like Tumbleweed kernels have that config option enabled by
default.  And it this feature was introduced in 5.4 (the bug doesn't seem
to be reproducible in 5.3).

Can you try adding this patch?

https://git.infradead.org/users/willy/pagecache.git/commitdiff/369a4fcd78369b7a026bdef465af9669bde98ef4

Yep, sure.  Unfortunately, the testing round-trip can be a bit high.  I'll
push a new kernel build and ask the reporter to give it a try.

[ I'll add this patch on top of the s/BUG_ON/VM_BUG_ON_PAGE change. ]

Cheers,
--
Luís