From nobody Sun Jul 19 15:13:58 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 4h36cQ58D4z6fgb1 for ; Sun, 19 Jul 2026 15:13:58 +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 4h36cQ4KxBz3rsF for ; Sun, 19 Jul 2026 15:13:58 +0000 (UTC) (envelope-from git@FreeBSD.org) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=freebsd.org; s=dkim; t=1784474038; 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=zDCqhEdVCgYtlzJ1/yionXKm7QPXCxKcksuCA6bRIAc=; b=l9VB6tntAdun9yyN6Kn1zhU0umhuii4Q3pXLnVm7P11YNzS7Xbihk3Tu7qu8l9kKbkyqT8 a/8kmXTEUhxMxErugGJZ9W6xi4Kq7d9KOqECR5MKZIxFpGg9qDHKS9vTL9wJPayE3duIdT ttTpjTLIDCTAln3SGzvNksRfkbPiJ9RXrhyorn5Y+oQTH3rgHNb+A9aF7eKxLKmyxFh6jQ 3EpoW8VdKTCVaWyKRXg95hm0sZvWRgn0uNoOCT+T4czRaq2fFXi5NeHcFzG5f3LVq+RyEx SHOsOHXINyZDC1PD9syv/H6/2XVs2ZgR+cyhLy5a6qsY7NTt9VNOMUVGDOZtGg== ARC-Seal: i=1; s=dkim; d=freebsd.org; t=1784474038; a=rsa-sha256; cv=none; b=cEW90wrOxWkAMyMc0prACkWgU5b/O6r+T/aX+xns3vgq2nlSIJfAIu0c3FT/8XvqhskUCf aunCA4HFq/l2swNdYNIDGTv9/tN+IHg5K+ZcSzd6ZpTUCsESMtPzNBLt5gz20PSaYO0DGf AyBgEc3laPhQv7495IVsgL+AC7p3abIeDnwNAgtDHcLysEumPe6meD2VoOU2gR/mQq/ehO E6HeQvL+E30qqglGBGsFXeBVkrQwZFNBfk60z0qwGW26E6gGp8MHXUe3WMMY81AtdpYOeP 5PtRPrPSM83XLAGNirGqtAk1j3m4A6d9+ROYVZin56iig3sR6NLcVEwHJ2v/jw== 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=1784474038; 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=zDCqhEdVCgYtlzJ1/yionXKm7QPXCxKcksuCA6bRIAc=; b=yE3DJ4bUFMEqC5y+wnR3B4smWySZlKK1SA4CVoPUXP2jAYFUOG//iI5bi7goqTyEBrgDlW CykrMdnxC3I/J4pE/JQt2qCwRyqFLIv3OeJ9ZjjI8kGuykd/nCiGMquSbPLDWxgLP/xJr0 qKeSweutKIkDXVB5UGS0He68L3ZQhZgNS/hz7tgv4zW7SfALAwNtuaSU9p0dpS3Fbb+ECN 15ZGe6UVzm4c2oWqf1tUN/7VflQW+bqRZw0jX9n5XqKnug/OIjnyM3c1Pt8f1AHEpyQykX SInMoMi8V9WHoQwozfoAEp54NXaXEM/5k2AuaWDT/bCHWxThSTmLLJymTZ8baQ== Received: from gitrepo.freebsd.org (gitrepo.freebsd.org [IPv6:2610:1c1:1:6068::e6a:5]) by mxrelay.nyi.freebsd.org (Postfix) with ESMTP id 4h36cQ31W0z4yg for ; Sun, 19 Jul 2026 15:13:58 +0000 (UTC) (envelope-from git@FreeBSD.org) Received: from git (uid 1279) (envelope-from git@FreeBSD.org) id 21080 by gitrepo.freebsd.org (DragonFly Mail Agent v0.13+ on gitrepo.freebsd.org); Sun, 19 Jul 2026 15:13:58 +0000 To: src-committers@FreeBSD.org, dev-commits-src-all@FreeBSD.org, dev-commits-src-main@FreeBSD.org From: Alexander Leidinger Subject: git: d6915bffb7b6 - main - 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/main X-Git-Reftype: branch X-Git-Commit: d6915bffb7b68d9b55fa3db4e5709463549c379e Auto-Submitted: auto-generated Date: Sun, 19 Jul 2026 15:13:58 +0000 Message-Id: <6a5ce9b6.21080.28e0c812@gitrepo.freebsd.org> The branch main has been updated by netchild: URL: https://cgit.FreeBSD.org/src/commit/?id=d6915bffb7b68d9b55fa3db4e5709463549c379e commit d6915bffb7b68d9b55fa3db4e5709463549c379e Author: Alexander Leidinger AuthorDate: 2026-07-19 07:38:52 +0000 Commit: Alexander Leidinger CommitDate: 2026-07-19 15:13:40 +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) --- 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 50d359c9b909..41823d0c6202 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); } /*