Forwarded: [PATCH] btrfs: debug folio_alloc_buffers parameters

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Subject: [PATCH] btrfs: debug folio_alloc_buffers parameters
Author: kartikey406@gmail.com

#syz test: git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master

Debug patch to understand NULL pointer dereference in create_empty_buffers.
Print folio_size and blocksize to identify why folio_alloc_buffers returns NULL.

NOT FOR MERGE - debug only.

Signed-off-by: Deepanshu Kartikey <kartikey406@gmail.com>
---
 fs/buffer.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fs/buffer.c b/fs/buffer.c
index 838c0c571022..487a32faaa16 100644
--- a/fs/buffer.c
+++ b/fs/buffer.c
@@ -928,7 +928,7 @@ struct buffer_head *folio_alloc_buffers(struct folio *folio, unsigned long size,
 	/* The folio lock pins the memcg */
 	memcg = folio_memcg(folio);
 	old_memcg = set_active_memcg(memcg);
-
+	pr_err("DEBUG: folio_size=%lu blocksize=%lu\n",folio_size(folio), size);
 	head = NULL;
 	offset = folio_size(folio);
 	while ((offset -= size) >= 0) {
-- 
2.43.0