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-rw-r--r--fs/xfs/xfs_buf.c11
1 files changed, 11 insertions, 0 deletions
diff --git a/fs/xfs/xfs_buf.c b/fs/xfs/xfs_buf.c
index 9c061ef..107f2fd 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;
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