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Commit 9ba1fb2c authored by Michal Hocko's avatar Michal Hocko Committed by Linus Torvalds
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xfs: use memalloc_nofs_{save,restore} instead of memalloc_noio* 

kmem_zalloc_large and _xfs_buf_map_pages use memalloc_noio_{save,restore}
API to prevent from reclaim recursion into the fs because vmalloc can
invoke unconditional GFP_KERNEL allocations and these functions might be
called from the NOFS contexts.  The memalloc_noio_save will enforce
GFP_NOIO context which is even weaker than GFP_NOFS and that seems to be
unnecessary.  Let's use memalloc_nofs_{save,restore} instead as it
should provide exactly what we need here - implicit GFP_NOFS context.

Link: http://lkml.kernel.org/r/20170306131408.9828-6-mhocko@kernel.org


Signed-off-by: default avatarMichal Hocko <mhocko@suse.com>
Reviewed-by: default avatarBrian Foster <bfoster@redhat.com>
Reviewed-by: default avatarDarrick J. Wong <darrick.wong@oracle.com>
Acked-by: default avatarVlastimil Babka <vbabka@suse.cz>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Theodore Ts'o <tytso@mit.edu>
Cc: Chris Mason <clm@fb.com>
Cc: David Sterba <dsterba@suse.cz>
Cc: Jan Kara <jack@suse.cz>
Cc: Nikolay Borisov <nborisov@suse.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 7dea19f9

fs/xfs/kmem.c

+6 −6
Original line number Diff line number Diff line
@@ -48,7 +48,7 @@ kmem_alloc(size_t size, xfs_km_flags_t flags) 
void *

kmem_zalloc_large(size_t size, xfs_km_flags_t flags)

{

	unsigned noio_flag = 0;

	unsigned nofs_flag = 0;

	void	*ptr;

	gfp_t	lflags;
@@ -60,17 +60,17 @@ kmem_zalloc_large(size_t size, xfs_km_flags_t flags) 
	 * __vmalloc() will allocate data pages and auxillary structures (e.g.

	 * pagetables) with GFP_KERNEL, yet we may be under GFP_NOFS context

	 * here. Hence we need to tell memory reclaim that we are in such a

	 * context via PF_MEMALLOC_NOIO to prevent memory reclaim re-entering

	 * context via PF_MEMALLOC_NOFS to prevent memory reclaim re-entering

	 * the filesystem here and potentially deadlocking.

	 */

	if ((current->flags & PF_MEMALLOC_NOFS) || (flags & KM_NOFS))

		noio_flag = memalloc_noio_save();

	if (flags & KM_NOFS)

		nofs_flag = memalloc_nofs_save();



	lflags = kmem_flags_convert(flags);

	ptr = __vmalloc(size, lflags | __GFP_HIGHMEM | __GFP_ZERO, PAGE_KERNEL);



	if ((current->flags & PF_MEMALLOC_NOFS) || (flags & KM_NOFS))

		memalloc_noio_restore(noio_flag);

	if (flags & KM_NOFS)

		memalloc_nofs_restore(nofs_flag);



	return ptr;

}

fs/xfs/xfs_buf.c

+4 −4
Original line number Diff line number Diff line
@@ -443,17 +443,17 @@ _xfs_buf_map_pages( 
		bp->b_addr = NULL;

	} else {

		int retried = 0;

		unsigned noio_flag;

		unsigned nofs_flag;



		/*

		 * vm_map_ram() will allocate auxillary structures (e.g.

		 * pagetables) with GFP_KERNEL, yet we are likely to be under

		 * GFP_NOFS context here. Hence we need to tell memory reclaim

		 * that we are in such a context via PF_MEMALLOC_NOIO to prevent

		 * that we are in such a context via PF_MEMALLOC_NOFS to prevent

		 * memory reclaim re-entering the filesystem here and

		 * potentially deadlocking.

		 */

		noio_flag = memalloc_noio_save();

		nofs_flag = memalloc_nofs_save();

		do {

			bp->b_addr = vm_map_ram(bp->b_pages, bp->b_page_count,

						-1, PAGE_KERNEL);
@@ -461,7 +461,7 @@ _xfs_buf_map_pages( 
				break;

			vm_unmap_aliases();

		} while (retried++ <= 1);

		memalloc_noio_restore(noio_flag);

		memalloc_nofs_restore(nofs_flag);



		if (!bp->b_addr)

			return -ENOMEM;