On Fri, 21 Mar 2014 13:00:55 -0700 Andrew Morton <a...@linux-foundation.org> wrote:
> On Fri, 21 Mar 2014 17:18:30 +0100 Fabian Frederick <f...@skynet.be> wrote: > > > Loop around congestion_wait on allocation failure/alloc_journal_list > > like already fixed in other FS. > > > > ... > > > > --- a/fs/reiserfs/journal.c > > +++ b/fs/reiserfs/journal.c > > @@ -2487,8 +2487,13 @@ static int journal_read(struct super_block *sb) > > static struct reiserfs_journal_list *alloc_journal_list(struct super_block > > *s) > > { > > struct reiserfs_journal_list *jl; > > - jl = kzalloc(sizeof(struct reiserfs_journal_list), > > - GFP_NOFS | __GFP_NOFAIL); > > + > > + do { > > + jl = kzalloc(sizeof(struct reiserfs_journal_list), GFP_NOFS); > > + if (unlikely(!jl)) > > + congestion_wait(BLK_RW_ASYNC, HZ/50); > > + } while (!jl) > > + > > Dammit, who has been running around converting __GFP_NOFAIL into > open-coded congestion_wait() loops? > > The whole point of __GFP_NOFAIL is to centralise this > wait-for-memory-for-ever operation. So it is implemented in a common > (core) place and so that we can easily locate these problematic > callers. > > This comment in ext4: > > /* > * If __GFP_FS is not present, then we may be > * being called from inside the fs writeback > * layer, so we MUST NOT fail. Since > * __GFP_NOFAIL is going away, we will arrange > * to retry the allocation ourselves. > */ > > is exactly wrong. Yes, we'd like __GFP_NOFAIL to go away, but it > cannot go away until buggy callsites such as this one are *fixed*. > Removing the __GFP_NOFAIL usage simply hides the buggy code from casual > searchers. > > argh. > > What we should do is to fix all these call sites so they can handle > memory exhaustion. That's hard so in the interim they should be using > __GFP_NOFAIL. > Ok, if even ext4 comments are wrong, things gonna be very difficult :) Any sample of a callsite transition done well ? (git id ?) -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/