On Wed, Sep 30, 2015 at 02:26:24PM +0200, Vlastimil Babka wrote: > [+CC lustre maintainers] > > On 09/29/2015 03:35 PM, Mel Gorman wrote: > >>>Ok, I'll add a TODO to create a patch that removes GFP_IOFS entirely. It > >>>can be tacked on to the end of the series. > >> > >>Okay, that makes sense to me. Thanks! > >> > > > >This? > > Thanks for adding this, I think I also pointed this GFP_IOFS oddness in > earlier versions. > > >---8<--- > >mm: page_alloc: Remove GFP_IOFS > > > >GFP_IOFS was intended to be shorthand for clearing two flags, not a > >set of allocation flags. There is only one user of this flag combination > >now and there appears to be no reason why Lustre had to be protected > > Looks like a mistake to me. __GFP_IO | __GFP_FS have no effect without > (former) __GFP_WAIT, so I doubt __GFP_WAIT was omitted on purpose, while > leaving the other two. The naming of GFP_IOFS suggested it was to be used in > allocations, leading to the mistake. > GFP_IOFS is shorthand clearing bits and should not have been used as an allocation flag. Using it as an allocation flag is almost certainly a mistake. At a stretch, GFP_IOFS could make sense if we supprted page reclaim that does not block (e.g. discard clean pages without buffers to release) but we don't. > But I see you also converted several instances of GFP_NOFS to GFP_KERNEL. Is > that correct? This is a filesystem driver after all... > Only in the cases where a reclaim path is reentrant and could already be holding locks that results in deadlock. I didn't spot such a case but then again, I'm not familiar with the filesystem and it's complex. Lets see what they say because how they are currently using GFP_IOFS is almost certainly wrong or at least surprising. > >diff --git a/drivers/staging/lustre/lustre/libcfs/tracefile.c b/drivers/staging/lustre/lustre/libcfs/tracefile.c > >index effa2af58c13..a7d72f69c4eb 100644 > >--- a/drivers/staging/lustre/lustre/libcfs/tracefile.c > >+++ b/drivers/staging/lustre/lustre/libcfs/tracefile.c > >@@ -810,7 +810,7 @@ int cfs_trace_allocate_string_buffer(char **str, int nob) > > if (nob > 2 * PAGE_CACHE_SIZE) /* string must be "sensible" */ > > return -EINVAL; > > > >- *str = kmalloc(nob, GFP_IOFS | __GFP_ZERO); > >+ *str = kmalloc(nob, GFP_KERNEL | __GFP_ZERO); > > This could use kzalloc. > True. -- Mel Gorman SUSE Labs -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>