On Thu, 11 Jan 2024 15:31:12 +0000, Matthew Wilcox wrote:
I do not understand the crash, and I do not understand why this patch would fix it. Can you explain either?
The WARNING appears in the following location: https://elixir.bootlin.com/linux/v5.10.205/source/fs/ext4/inode.c#L3693
Reverse bisection pointed at the 2nd patch as a fix, but after backporting this patch to 5.10 branch I still hit the WARNING. I noticed that there was some missing code compared to the original patch:
if (folio_has_private(folio) && !filemap_release_folio(folio, 0)) return 0;
Then I found a patch with this code before using folio, applied it, and tests showed the WARNING disappeared. I also used the linux test project to make sure nothing was broken. I'll try to dig a little deeper and explain the crash.
Thanks for the reply.