If the NFS client is doing writeback from a workqueue context, avoid using
__GFP_NORETRY for allocations if the task has set PF_MEMALLOC_NOIO or
PF_MEMALLOC_NOFS. The combination of these flags makes memory allocation
failures much more likely.
We've seen those allocation failures show up when the loopback driver is
doing writeback from a workqueue to a file on NFS, where memory allocation
failure results in errors or corruption within the loopback device's
filesystem.
Suggested-by: Trond Myklebust <trondmy@xxxxxxxxxx>
Fixes: 0bae835b63c5 ("NFS: Avoid writeback threads getting stuck in mempool_alloc()")
Signed-off-by: Benjamin Coddington <bcodding@xxxxxxxxxx>
Reviewed-by: Laurence Oberman <loberman@xxxxxxxxxx>
Tested-by: Laurence Oberman <loberman@xxxxxxxxxx>
Reviewed-by: Jeff Layton <jlayton@xxxxxxxxxx>
---
On V3: fix ugly return (Thanks Paulo), add Jeff's R-b
On V2: add missing 'Fixes' and Laurence's R-b T-b
fs/nfs/internal.h | 9 ++++++---
1 file changed, 6 insertions(+), 3 deletions(-)
diff --git a/fs/nfs/internal.h b/fs/nfs/internal.h
index 69c2c10ee658..d8f768254f16 100644
--- a/fs/nfs/internal.h
+++ b/fs/nfs/internal.h
@@ -671,9 +671,12 @@ nfs_write_match_verf(const struct nfs_writeverf *verf,
static inline gfp_t nfs_io_gfp_mask(void)
{
- if (current->flags & PF_WQ_WORKER)
- return GFP_KERNEL | __GFP_NORETRY | __GFP_NOWARN;
- return GFP_KERNEL;
+ gfp_t ret = current_gfp_context(GFP_KERNEL);
+
+ /* For workers __GFP_NORETRY only with __GFP_IO or __GFP_FS */
+ if ((current->flags & PF_WQ_WORKER) && ret == GFP_KERNEL)
+ ret |= __GFP_NORETRY | __GFP_NOWARN;
+ return ret;
}
/*
--
2.47.0
