From nobody Mon Dec 1 23:34:49 2025 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 187D04C9D; Wed, 26 Nov 2025 05:41:32 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1764135693; cv=none; b=RjSWrNC/ymukB0mtql/fGnvfSwPqNn3F/llq0sIx09wUTwQhKzfMjlH6U7CcAjmfQIFvznQY3Tq7929e/QErpbr6904eYDLNfbIU5s3hr5YUfUZU4ArO2+dsyB1p/FvCeAsLtlEH1pmORH0XnVoTo9yodFCGO2wMv+D031jCkBQ= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1764135693; c=relaxed/simple; bh=GMXu/4I7zzQgm+L6w7tz8iBYxeVA2h+/HGxG6IsCMB4=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=TqqD6SHknyP8UPItUKUKGBykKS3EtBTAKEvgweBZZvTJmSdwPdnPmwEh/+S/AwlfECFzlijq3con0N8FdE9rrZD+eM3jNVu28a3gCASFZcjWWA4co4ArXP9XORorEBZ0O3b6UVYZN7f6QhG7E+6cQISflHgFJ6IV4T9Rhfdq+hw= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=TahFNRri; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="TahFNRri" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 53D02C113D0; Wed, 26 Nov 2025 05:41:32 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1764135692; bh=GMXu/4I7zzQgm+L6w7tz8iBYxeVA2h+/HGxG6IsCMB4=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=TahFNRrixa1ahnAx5yvZIRY6cqyUo0Sj/jW1lxpYn7a1SpZtu9ygTQ4juSRuMrQQv jhQjSmpJZIi40yjGVFQcK6r5gD7Tw7zYH9XIy9gopBZ5hgGrVXTWZPkzAsskus6h4I jP4s/8L/kvP/nsJlPtPBTnNW5D8UgvEUm6kJwtmTZQAdAtetF9o83phjNr2R4c8qF7 ri1uy57Kl9TiFmLqCdbq0aYSMDhiQDVMWyfJeOLHvCiC8D+rK1RJ68oYxqlxMS/nKD BOLC/LKbAtKcRtIHRDuBsSw6s546ZNQJkPOOnxb1y2LhofIlVYKTIxcap/cUczFO7V vm4GrzCUVC7Yw== Date: Wed, 26 Nov 2025 00:41:31 -0500 From: Mike Snitzer To: Zorro Lang , anna@kernel.org Cc: linux-nfs@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH] nfs/localio: fix regression due to out-of-order __put_cred [was: Re: [Bug][xfstests crash on nfs] kernel BUG at kernel/cred.c:104!] Message-ID: References: <20251125144508.rxepvtwrubbuhzxs@dell-per750-06-vm-08.rhts.eng.pek2.redhat.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20251125144508.rxepvtwrubbuhzxs@dell-per750-06-vm-08.rhts.eng.pek2.redhat.com> Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" Commit 86855311c117 ("nfs/localio: add refcounting for each iocb IO associated with NFS pgio header") inadvertantly reintroduced the same potential for __put_cred() triggering BUG_ON(cred =3D=3D current->cred) that commit 992203a1fba5 ("nfs/localio: restore creds before releasing pageio data") fixed. Fix this by saving and restoring the cred around each {read,write}_iter=20 call within the respective for loop of nfs_local_call_{read,write}. Reported-by: Zorro Lang Fixes: 86855311c117 ("nfs/localio: add refcounting for each iocb IO associa= ted with NFS pgio header") Signed-off-by: Mike Snitzer diff --git a/fs/nfs/localio.c b/fs/nfs/localio.c index 6461ce3ba9a4..eeb05a0d8d26 100644 --- a/fs/nfs/localio.c +++ b/fs/nfs/localio.c @@ -623,8 +623,6 @@ static void nfs_local_call_read(struct work_struct *wor= k) ssize_t status; int n_iters; =20 - save_cred =3D override_creds(filp->f_cred); - n_iters =3D atomic_read(&iocb->n_iters); for (int i =3D 0; i < n_iters ; i++) { if (iocb->iter_is_dio_aligned[i]) { @@ -637,7 +635,10 @@ static void nfs_local_call_read(struct work_struct *wo= rk) } else iocb->kiocb.ki_flags &=3D ~IOCB_DIRECT; =20 + save_cred =3D override_creds(filp->f_cred); status =3D filp->f_op->read_iter(&iocb->kiocb, &iocb->iters[i]); + revert_creds(save_cred); + if (status !=3D -EIOCBQUEUED) { if (unlikely(status >=3D 0 && status < iocb->iters[i].count)) force_done =3D true; /* Partial read */ @@ -647,8 +648,6 @@ static void nfs_local_call_read(struct work_struct *wor= k) } } } - - revert_creds(save_cred); } =20 static int @@ -830,7 +829,6 @@ static void nfs_local_call_write(struct work_struct *wo= rk) int n_iters; =20 current->flags |=3D PF_LOCAL_THROTTLE | PF_MEMALLOC_NOIO; - save_cred =3D override_creds(filp->f_cred); =20 file_start_write(filp); n_iters =3D atomic_read(&iocb->n_iters); @@ -845,7 +843,10 @@ static void nfs_local_call_write(struct work_struct *w= ork) } else iocb->kiocb.ki_flags &=3D ~IOCB_DIRECT; =20 + save_cred =3D override_creds(filp->f_cred); status =3D filp->f_op->write_iter(&iocb->kiocb, &iocb->iters[i]); + revert_creds(save_cred); + if (status !=3D -EIOCBQUEUED) { if (unlikely(status >=3D 0 && status < iocb->iters[i].count)) force_done =3D true; /* Partial write */ @@ -857,7 +858,6 @@ static void nfs_local_call_write(struct work_struct *wo= rk) } file_end_write(filp); =20 - revert_creds(save_cred); current->flags =3D old_flags; }