From nobody Sun Aug 2 12:12:51 2026 X-Original-To: dev-commits-src-all@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 4hCdx02B0nz6nQly for ; Sun, 02 Aug 2026 12:12:52 +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 4hCdx00y5wz3mB4 for ; Sun, 02 Aug 2026 12:12:52 +0000 (UTC) (envelope-from git@FreeBSD.org) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=freebsd.org; s=dkim; t=1785672772; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding; bh=UrkXN4sZ8Y3JONmC2ZuPMdbVv8OAgLG7n8f9U8+LvKQ=; b=NScQVeWCUxqHZST+x55CAkO0+gjcigs4tpBg+D98tHFSeei1lIjncbvj0vKGz66PnTKrog 7IGKZCN32FjnFw0LrC0Vi9uIqSgw2uYjp/563cUp00/crMwNwjW6wXJxMbxlEmexrL6vZ/ S4U5sKymD91o6qklVGO5VFCnSFaF8ugKitlJtieDWidGGSjqZzxkaga589WYssldt0mahG tNFpGfOyy0wjDPyPAyZ9iXK8QsXt0lDt01hHSA175pHMg/HOulniDAh35eGVw6JmkHoEkh bHyG4ozxoIN9CpjaO41PFFxnINf+w7Ajbs7xKwzcFTx8+guZ4Bcd5F9qeN9yjw== ARC-Seal: i=1; s=dkim; d=freebsd.org; t=1785672772; a=rsa-sha256; cv=none; b=Iza4vMfpiB6MznzvAuWIorVX3HwQ3DhbMCErs8HA22ibgTDeZpQHBMc9s0aZe2b+jS7TUW KxQvA5DkXtl6N+JLIQGdfmWQTbZ1tgthcLnceF5LE5g+VIa0pqEc7ulm9F9TJO42fus9YX OOj5PX0zrYBHxiX9CI7CsNqohqPdFY9wKbmfT/7ZnTgAgO5MWpbTb1hRvyJ2QqT1cWWPm8 Bn/gHqww2+p4tiyejuHlMzTtMGtiYtBQwJIOWInXAawYFJg6tEho98+J9ssSi63WfiPa5V 8Grsvp/BziqinV6DGaW+5FGweAmtjTC/Ikkz8eGyqbO/xwswnrdzn+qgQod8TA== 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=1785672772; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding; bh=UrkXN4sZ8Y3JONmC2ZuPMdbVv8OAgLG7n8f9U8+LvKQ=; b=Wm4V5G+RHak7vgLqAOTDFORlYhbKmsHFueMbOIjgW0z5vDZi/eRwzynjzQMHpxDDgZ6E+F Kj11zkKwMkyBmTUt9TYZgwV5y+eSaSfBSP5t4TaMyj4j/rd56Wmx7+m6BYUVnaweOuFVdC pJddABj7BihPofFjYvkUVoLsmLDTNScKqBsVuOmZjj0awCdlElrot/j7C6umUcJeMhDXO3 ZL0KwYeYEXBfdpklK6d7UWGbp4tTaQDkjTQSck+9wfD9xOcbDKAPJCOAomFkvjS8lW2tQU nJ2Qik247LCBOYNswufpz/VXx54qLYO29rnqs0Cm3uBpmqtbXtIgqM6TF790+w== Received: from gitrepo.freebsd.org (gitrepo.freebsd.org [IPv6:2610:1c1:1:6068::e6a:5]) by mxrelay.nyi.freebsd.org (Postfix) with ESMTP id 4hCdwz6lrKz1SHJ for ; Sun, 02 Aug 2026 12:12:51 +0000 (UTC) (envelope-from git@FreeBSD.org) Received: from git (uid 1279) (envelope-from git@FreeBSD.org) id 1d960 by gitrepo.freebsd.org (DragonFly Mail Agent v0.13+ on gitrepo.freebsd.org); Sun, 02 Aug 2026 12:12:51 +0000 To: src-committers@FreeBSD.org, dev-commits-src-all@FreeBSD.org, dev-commits-src-branches@FreeBSD.org From: Alexander Leidinger Subject: git: a5a16ba5f179 - stable/15 - nullfs: close a race when syncing inotify flags from the lower vnode List-Id: Commit messages for all branches of the src repository List-Archive: https://lists.freebsd.org/archives/dev-commits-src-all List-Help: List-Post: List-Subscribe: List-Unsubscribe: X-BeenThere: dev-commits-src-all@freebsd.org Sender: owner-dev-commits-src-all@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: netchild X-Git-Repository: src X-Git-Refname: refs/heads/stable/15 X-Git-Reftype: branch X-Git-Commit: a5a16ba5f1791e1be87fede24887b469a9a0d911 Auto-Submitted: auto-generated Date: Sun, 02 Aug 2026 12:12:51 +0000 Message-Id: <6a6f3443.1d960.1fc3afd9@gitrepo.freebsd.org> The branch stable/15 has been updated by netchild: URL: https://cgit.FreeBSD.org/src/commit/?id=a5a16ba5f1791e1be87fede24887b469a9a0d911 commit a5a16ba5f1791e1be87fede24887b469a9a0d911 Author: Alexander Leidinger AuthorDate: 2026-07-19 07:38:52 +0000 Commit: Alexander Leidinger CommitDate: 2026-08-02 12:12:07 +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 ee7d89db6b05..27ccb54c2a4f 100644 --- a/sys/fs/nullfs/null_vnops.c +++ b/sys/fs/nullfs/null_vnops.c @@ -196,17 +196,26 @@ 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); } /*