[23/37] xfs: use kvmalloc for xattr buffers

Commit Message

Darrick J. Wong Oct. 21, 2024, 10:04 p.m. UTC

From: Dave Chinner <[e-mail]>

Source kernel commit: de631e1a8b71017b8a12b57d07db82e4052555af

Pankaj Raghav reported that when filesystem block size is larger
than page size, the xattr code can use kmalloc() for high order
allocations. This triggers a useless warning in the allocator as it
is a __GFP_NOFAIL allocation here:

static inline
struct page *rmqueue(struct zone *preferred_zone,
struct zone *zone, unsigned int order,
gfp_t gfp_flags, unsigned int alloc_flags,
int migratetype)
{
struct page *page;

/*
* We most definitely don't want callers attempting to
* allocate greater than order-1 page units with __GFP_NOFAIL.
*/
>>>>    WARN_ON_ONCE((gfp_flags & __GFP_NOFAIL) && (order > 1));
...

Fix this by changing all these call sites to use kvmalloc(), which
will strip the NOFAIL from the kmalloc attempt and if that fails
will do a __GFP_NOFAIL vmalloc().

This is not an issue that productions systems will see as
filesystems with block size > page size cannot be mounted by the
kernel; Pankaj is developing this functionality right now.

Reported-by: Pankaj Raghav <[e-mail]>
Fixes: f078d4ea8276 ("xfs: convert kmem_alloc() to kmalloc()")
Signed-off-by: Dave Chinner <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Reviewed-by: Darrick J. Wong <[e-mail]>
Reviewed-by: Pankaj Raghav <[e-mail]>
Reviewed-by: Hannes Reinecke <[e-mail]>
Signed-off-by: Christoph Hellwig <[e-mail]>
Acked-by: Darrick J. Wong <[e-mail]>
Reviewed-by: Daniel Gomez <[e-mail]>
Reviewed-by: Dave Chinner <[e-mail]>
Reviewed-by: Matthew Wilcox (Oracle) <[e-mail]>
Signed-off-by: Christian Brauner <[e-mail]>
---
 include/kmem.h         |    6 ++++++
 libxfs/xfs_attr_leaf.c |   15 ++++++---------
 2 files changed, 12 insertions(+), 9 deletions(-)

Patch

diff --git a/include/kmem.h b/include/kmem.h
index 8dfb2fb0b45020..8739d824008e2a 100644
--- a/include/kmem.h
+++ b/include/kmem.h
@@ -59,12 +59,18 @@  static inline void *kmalloc(size_t size, gfp_t flags)
 }
 
 #define kzalloc(size, gfp)	kvmalloc((size), (gfp) | __GFP_ZERO)
+#define kvzalloc(size, gfp)	kzalloc((size), (gfp))
 
 static inline void kfree(const void *ptr)
 {
 	free((void *)ptr);
 }
 
+static inline void kvfree(const void *ptr)
+{
+	kfree(ptr);
+}
+
 __attribute__((format(printf,2,3)))
 char *kasprintf(gfp_t gfp, const char *fmt, ...);
 
diff --git a/libxfs/xfs_attr_leaf.c b/libxfs/xfs_attr_leaf.c
index 97b71b6500bdc9..db2e48d719d36f 100644
--- a/libxfs/xfs_attr_leaf.c
+++ b/libxfs/xfs_attr_leaf.c
@@ -1135,10 +1135,7 @@  xfs_attr3_leaf_to_shortform(
 
 	trace_xfs_attr_leaf_to_sf(args);
 
-	tmpbuffer = kmalloc(args->geo->blksize, GFP_KERNEL | __GFP_NOFAIL);
-	if (!tmpbuffer)
-		return -ENOMEM;
-
+	tmpbuffer = kvmalloc(args->geo->blksize, GFP_KERNEL | __GFP_NOFAIL);
 	memcpy(tmpbuffer, bp->b_addr, args->geo->blksize);
 
 	leaf = (xfs_attr_leafblock_t *)tmpbuffer;
@@ -1202,7 +1199,7 @@  xfs_attr3_leaf_to_shortform(
 	error = 0;
 
 out:
-	kfree(tmpbuffer);
+	kvfree(tmpbuffer);
 	return error;
 }
 
@@ -1610,7 +1607,7 @@  xfs_attr3_leaf_compact(
 
 	trace_xfs_attr_leaf_compact(args);
 
-	tmpbuffer = kmalloc(args->geo->blksize, GFP_KERNEL | __GFP_NOFAIL);
+	tmpbuffer = kvmalloc(args->geo->blksize, GFP_KERNEL | __GFP_NOFAIL);
 	memcpy(tmpbuffer, bp->b_addr, args->geo->blksize);
 	memset(bp->b_addr, 0, args->geo->blksize);
 	leaf_src = (xfs_attr_leafblock_t *)tmpbuffer;
@@ -1648,7 +1645,7 @@  xfs_attr3_leaf_compact(
 	 */
 	xfs_trans_log_buf(trans, bp, 0, args->geo->blksize - 1);
 
-	kfree(tmpbuffer);
+	kvfree(tmpbuffer);
 }
 
 /*
@@ -2327,7 +2324,7 @@  xfs_attr3_leaf_unbalance(
 		struct xfs_attr_leafblock *tmp_leaf;
 		struct xfs_attr3_icleaf_hdr tmphdr;
 
-		tmp_leaf = kzalloc(state->args->geo->blksize,
+		tmp_leaf = kvzalloc(state->args->geo->blksize,
 				GFP_KERNEL | __GFP_NOFAIL);
 
 		/*
@@ -2368,7 +2365,7 @@  xfs_attr3_leaf_unbalance(
 		}
 		memcpy(save_leaf, tmp_leaf, state->args->geo->blksize);
 		savehdr = tmphdr; /* struct copy */
-		kfree(tmp_leaf);
+		kvfree(tmp_leaf);
 	}
 
 	xfs_attr3_leaf_hdr_to_disk(state->args->geo, save_leaf, &savehdr);