From nobody Wed Aug 5 15:16:47 2026 X-Original-To: dev-commits-src-branches@mlmmj.nyi.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2610:1c1:1:606c::19:1]) by mlmmj.nyi.freebsd.org (Postfix) with ESMTP id 4hFYsq6WGmz6nQjQ for ; Wed, 05 Aug 2026 15:16:47 +0000 (UTC) (envelope-from git@FreeBSD.org) Received: from mxrelay.nyi.freebsd.org (mxrelay.nyi.freebsd.org [IPv6:2610:1c1:1:606c::19:3]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256 client-signature RSA-PSS (4096 bits) client-digest SHA256) (Client CN "mxrelay.nyi.freebsd.org", Issuer "YR1" (not verified)) by mx1.freebsd.org (Postfix) with ESMTPS id 4hFYsq4LQyz3w89 for ; Wed, 05 Aug 2026 15:16:47 +0000 (UTC) (envelope-from git@FreeBSD.org) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=freebsd.org; s=dkim; t=1785943007; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding; bh=fWKs861O1weFFscH5Pvp0Bi3oaWK/0M8scWbgHg6UYA=; b=Gmch6MBYvLaTt88hwD1AGMjGEqNUEM2fqc4qJqbBKvkWifQku9vMJEc2MNFUOdGklCzxpG WHlCRl9kQm9z5AnATFteUejOxQgJF3j1AuGHwBLZZbnEF1ZeyVM2Ar8XIYRVsgNEh75Nhl SpBBh5At78EbuNpuyyOoFXqoP6paANkdUhfaRGQU+cHCI4aCkYbVShbOSxMjwYmI959NU1 x1RzyEaeihRmLIAiOn2Bw5uxC+6hBENiii61iXhhIlEMMsfdAxa3PoDPCGK2dkpBzwuePc DTE3c0V9nkWxEEjmcm6G1AxqiCu+o8kGCz6a2xofNvQoqPyeFpFMG+iL8PSvqg== ARC-Seal: i=1; s=dkim; d=freebsd.org; t=1785943007; a=rsa-sha256; cv=none; b=gK0SUZg6LfXUsmX5LEbg0s8eNMDDa8eN+CNg3ia0P7U7zCvR49ZfSsZ/n4SSw4lZ/Bmrnr iO0j4XeJXk4Xozs/SJrq2AIYCSPXCEhSp/zoNUzFZW96BPlRrMxwuOmHOvKmjUq03JeIsR vv+FFKO4vMDJhX2Umy9pQpcDJuuKHREYHX+KibEu/Ro3k4rwsRf5twcVnpntIK7rO5reW4 jkTBcXrBbz0jLjx4IiANg/K+cwv269FshUu7NHszGwaWCZ3tgUhOtlYKvUFfHHkwyDEe95 IRQjF0W5sPh/lrMPoEhnb4cozC24laBOjtA5e7m0o8n7SP+LDxzTxZfPmAA4/w== ARC-Authentication-Results: i=1; mx1.freebsd.org; none ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=freebsd.org; s=dkim; t=1785943007; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding; bh=fWKs861O1weFFscH5Pvp0Bi3oaWK/0M8scWbgHg6UYA=; b=YS9kKCd4b6oexViPtQy1/Te6UL1cK8IN3b7OsWZHoWgNXIVujmIsikoDpIrKRphv23O6aq 1ZaPDk/uGj3Gy3bo4k4YyI6Ntxkpxm4zYFURa9WGTBwJeoBv7VsaQ+zlpfA7azte5OD58C Wn0soJTwZOjsYRVPadg7E4UXfqxx+sqrK48qOmbKLeUs4To2j1+p/kbP+ow1/JLwKrU2DW s9bWWyuaLNT3tETOgYOe/dgYdbdtqIIcvUplQyw8kqX78BvO+qdVz8PdaRuPbzxW8/TBww YYoXKUUjj5bSN2JsTjBnmiCpesz/IMgHG/jiHujn9zpgyvmyBZf/GroaQTvfog== Received: from gitrepo.freebsd.org (gitrepo.freebsd.org [IPv6:2610:1c1:1:6068::e6a:5]) by mxrelay.nyi.freebsd.org (Postfix) with ESMTP id 4hFYsq3MQpzfs7 for ; Wed, 05 Aug 2026 15:16:47 +0000 (UTC) (envelope-from git@FreeBSD.org) Received: from git (uid 1279) (envelope-from git@FreeBSD.org) id 44fdf by gitrepo.freebsd.org (DragonFly Mail Agent v0.13+ on gitrepo.freebsd.org); Wed, 05 Aug 2026 15:16:47 +0000 To: src-committers@FreeBSD.org, dev-commits-src-all@FreeBSD.org, dev-commits-src-branches@FreeBSD.org Cc: Alexander Leidinger From: Mark Johnston Subject: git: 00c2ff02342d - stable/14 - nullfs: close a race when syncing inotify flags from the lower vnode List-Id: Commits to the stable branches of the FreeBSD src repository List-Archive: https://lists.freebsd.org/archives/dev-commits-src-branches List-Help: List-Post: List-Subscribe: List-Unsubscribe: X-BeenThere: dev-commits-src-branches@freebsd.org Sender: owner-dev-commits-src-branches@FreeBSD.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8bit X-Git-Committer: markj X-Git-Repository: src X-Git-Refname: refs/heads/stable/14 X-Git-Reftype: branch X-Git-Commit: 00c2ff02342d3f211c97f8b4ace9a5a96d955ea4 Auto-Submitted: auto-generated Date: Wed, 05 Aug 2026 15:16:47 +0000 Message-Id: <6a7353df.44fdf.47c4b60f@gitrepo.freebsd.org> The branch stable/14 has been updated by markj: URL: https://cgit.FreeBSD.org/src/commit/?id=00c2ff02342d3f211c97f8b4ace9a5a96d955ea4 commit 00c2ff02342d3f211c97f8b4ace9a5a96d955ea4 Author: Alexander Leidinger AuthorDate: 2026-07-19 07:38:52 +0000 Commit: Mark Johnston CommitDate: 2026-08-05 15:15:16 +0000 nullfs: close a race when syncing inotify flags from the lower vnode After a bypassed VOP, nullfs mirrors the lower vnode's inotify state onto the upper vnode. The flags were checked with lockless reads before being updated with the asserting flag set/unset primitives, so two threads syncing the same vnode concurrently (or a sync racing a watch being established) could both decide to make the same change; the loser then trips the "flags already set" assertion on an INVARIANTS kernel. On other kernels the race is harmless. Keep the lockless check as the fast path, but re-make the decision under the vnode interlock before actually changing the flags. Reproduced in a 4-CPU VM with one thread cycling an inotify watch on a lower-filesystem file while several threads stat(2) the same file through a nullfs mount: the unpatched INVARIANTS kernel panics under this load, the patched kernel runs it to completion. Fixes: f1f230439fa4 ("vfs: Initial revision of inotify") MFC after: 2 weeks Differential Revision: D58344 Reviewed by: markj Assisted-by: Claude Code (Fable 5) (cherry picked from commit d6915bffb7b68d9b55fa3db4e5709463549c379e) --- sys/fs/nullfs/null_vnops.c | 19 ++++++++++++++----- 1 file changed, 14 insertions(+), 5 deletions(-) diff --git a/sys/fs/nullfs/null_vnops.c b/sys/fs/nullfs/null_vnops.c index 6fe5dc64b4d7..9108cd338a45 100644 --- a/sys/fs/nullfs/null_vnops.c +++ b/sys/fs/nullfs/null_vnops.c @@ -200,17 +200,26 @@ SYSCTL_INT(_debug, OID_AUTO, nullfs_bug_bypass, CTLFLAG_RW, * VOP_INOTIFY. * - If the lower vnode is watched, then the upper vnode should go through * VOP_INOTIFY, so copy the flag up. + * + * The lockless check is only a fast path: the decision to change a flag + * is re-made under the upper vnode's interlock, since another thread may + * set or clear the flag concurrently. */ static void null_copy_inotify(struct vnode *vp, struct vnode *lvp, short flag) { + if (__predict_true((vn_irflag_read(vp) & flag) == + (vn_irflag_read(lvp) & flag))) + return; + VI_LOCK(vp); if ((vn_irflag_read(vp) & flag) != 0) { - if (__predict_false((vn_irflag_read(lvp) & flag) == 0)) - vn_irflag_unset(vp, flag); - } else if ((vn_irflag_read(lvp) & flag) != 0) { - if (__predict_false((vn_irflag_read(vp) & flag) == 0)) - vn_irflag_set(vp, flag); + if ((vn_irflag_read(lvp) & flag) == 0) + vn_irflag_unset_locked(vp, flag); + } else { + if ((vn_irflag_read(lvp) & flag) != 0) + vn_irflag_set_locked(vp, flag); } + VI_UNLOCK(vp); } /*