2 files changed, 31 insertions, 1 deletions

diff --git a/fs/xfs/kmem.c b/fs/xfs/kmem.c
index 66a36befc5c0..844e288b9576 100644
--- a/fs/xfs/kmem.c
+++ b/fs/xfs/kmem.c
@@ -65,12 +65,31 @@ 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;
         void    *ptr;
+        gfp_t   lflags;
 
         ptr = kmem_zalloc(size, flags | KM_MAYFAIL);
         if (ptr)
                 return ptr;
-        return vzalloc(size);
+
+        /*
+         * __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
+         * the filesystem here and potentially deadlocking.
+         */
+        if ((current->flags & PF_FSTRANS) || (flags & KM_NOFS))
+                noio_flag = memalloc_noio_save();
+
+        lflags = kmem_flags_convert(flags);
+        ptr = __vmalloc(size, lflags | __GFP_HIGHMEM | __GFP_ZERO, PAGE_KERNEL);
+
+        if ((current->flags & PF_FSTRANS) || (flags & KM_NOFS))
+                memalloc_noio_restore(noio_flag);
+
+        return ptr;
 }
 
 void
diff --git a/fs/xfs/xfs_buf.c b/fs/xfs/xfs_buf.c
index 9c061ef2b0d9..107f2fdfe41f 100644
--- a/fs/xfs/xfs_buf.c
+++ b/fs/xfs/xfs_buf.c
@@ -396,7 +396,17 @@ _xfs_buf_map_pages(
                 bp->b_addr = NULL;
         } else {
                 int retried = 0;
+                unsigned noio_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
+                 * memory reclaim re-entering the filesystem here and
+                 * potentially deadlocking.
+                 */
+                noio_flag = memalloc_noio_save();
                 do {
                         bp->b_addr = vm_map_ram(bp->b_pages, bp->b_page_count,
                                                 -1, PAGE_KERNEL);
@@ -404,6 +414,7 @@ _xfs_buf_map_pages(
                                 break;
                         vm_unmap_aliases();
                 } while (retried++ <= 1);
+                memalloc_noio_restore(noio_flag);
 
                 if (!bp->b_addr)
                         return -ENOMEM;