On Feb 26 2019, Miklos Szeredi <miklos@xxxxxxxxxx> wrote: > On Tue, Feb 26, 2019 at 9:35 PM Nikolaus Rath <Nikolaus@xxxxxxxx> wrote: >> >> [ Moving fuse-devel and linux-fsdevel to Bcc ] >> >> Hello linux-mm people, >> >> I am posting this here as advised by Miklos (see below). In short, I >> have a workload that reliably produces kernel messages of the form: >> >> [ 2562.773181] fuse: trying to steal weird page >> [ 2562.773187] page=<something> index=<something> flags=17ffffc00000ad, count=1, mapcount=0, mapping= (null) >> >> What are the implications of this message? Is something activelly going >> wrong (aka do I need to worry about data integrity)? > > Fuse is careful and basically just falls back on page copy, so it > definitely shouldn't affect data integrity. > > The more interesting question is: how can page_cache_pipe_buf_steal() > return a dirty page? The logic in remove_mapping() should prevent > that, but something is apparently slipping through... > >> >> Is there something I can do to help debugging (and hopefully fixing) >> this? >> >> This is with kernel 4.18 (from Ubuntu cosmic). > > One thought: have you tried reproducing with a recent vanilla > (non-ubuntu) kernel? Yes, I can reproduce with e.g. 5.0.0-050000rc8 (from https://kernel.ubuntu.com/~kernel-ppa/mainline/v5.0-rc8/). However, here the flag value is different: [ 278.183571] fuse: trying to steal weird page [ 278.183576] page=000000000aab208c index=14944 flags=17ffffc0000097, count=1, mapcount=0, mapping= (null) (but still the same across all messages observed with this kernel so far). Best, -Nikolaus -- GPG Fingerprint: ED31 791B 2C5C 1613 AF38 8B8A D113 FCAC 3C4E 599F »Time flies like an arrow, fruit flies like a Banana.«
