Forwarded: Re: [syzbot] WARNING in rgblk_free

[syzbot <syzbot+3e2c95229d1ab81a0bfd@syzkaller.appspotmail.com>]

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Subject: Re: [syzbot] WARNING in rgblk_free
Author: tristmd@gmail.com

#syz test: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
>From 4649cf253677e3ba7f3266916dfe24fecc0e3b69 Mon Sep 17 00:00:00 2001
From: Tristan Madani <tristan@talencesecurity.com>
Date: Fri, 17 Apr 2026 16:15:19 +0000
Subject: [PATCH] gfs2: replace WARN_ON_ONCE with error message in rgblk_free()
rgblk_free() uses WARN_ON_ONCE when gfs2_rbm_from_block() fails,
which triggers a kernel WARNING on corrupted filesystems. Replace
with fs_warn() to log the error without triggering a WARNING splat.
Reported-by: syzbot+3e2c95229d1ab81a0bfd@syzkaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=3e2c95229d1ab81a0bfd
Signed-off-by: Tristan Madani <tristan@talencesecurity.com>
---
 fs/gfs2/rgrp.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)
diff --git a/fs/gfs2/rgrp.c b/fs/gfs2/rgrp.c
index 5988a16..a7c1965 100644
--- a/fs/gfs2/rgrp.c
+++ b/fs/gfs2/rgrp.c
@@ -2264,8 +2264,11 @@ static void rgblk_free(struct gfs2_sbd *sdp, struct gfs2_rgrpd *rgd,
 	struct gfs2_bitmap *bi, *bi_prev = NULL;
 
 	rbm.rgd = rgd;
-	if (WARN_ON_ONCE(gfs2_rbm_from_block(&rbm, bstart)))
+	if (gfs2_rbm_from_block(&rbm, bstart)) {
+		fs_warn(sdp, "rgblk_free: block %llu outside rgrp\n",
+			(unsigned long long)bstart);
 		return;
+	}
 	while (blen--) {
 		bi = rbm_bi(&rbm);
 		if (bi != bi_prev) {
-- 
2.47.3