On Thu 11-02-21 11:22:25, Jan Kara wrote: > On Thu 11-02-21 12:07:29, Hillf Danton wrote: I haven't received Hillf's email. [...] > > Fix 71b565ceff37 ("ext4: drop ext4_kvmalloc()") by restoring the > > GFP_NOFS introduced in dec214d00e0d ("ext4: xattr inode deduplication"). > > > > Note this may be the fix also to possible deadlock > > Reported-by: syzbot+bfdded10ab7dcd7507ae@xxxxxxxxxxxxxxxxxxxxxxxxx > > https://lore.kernel.org/linux-ext4/000000000000563a0205bafb7970@xxxxxxxxxx/ > > Please no. Ext4 is using scoping API to limit allocations to GFP_NOFS > inside transactions. In this case something didn't work which seems like a > lockdep bug at the first sight but I'll talk to mm guys about it. > Definitely to problem doesn't seem to be in ext4. Agreed. kvmalloc(NOFS) is not even supported because vmalloc doesn't support GFP_KERNEL incompatible requests. > > Honza > > > > > --- a/fs/ext4/xattr.c > > +++ b/fs/ext4/xattr.c > > @@ -1459,7 +1459,7 @@ ext4_xattr_inode_cache_find(struct inode > > if (!ce) > > return NULL; > > > > - ea_data = kvmalloc(value_len, GFP_KERNEL); > > + ea_data = kvmalloc(value_len, GFP_NOFS); > > if (!ea_data) { > > mb_cache_entry_put(ea_inode_cache, ce); > > return NULL; > -- > Jan Kara <jack@xxxxxxxx> > SUSE Labs, CR -- Michal Hocko SUSE Labs