From mboxrd@z Thu Jan 1 00:00:00 1970 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 5EE30227E90; Thu, 13 Feb 2025 12:34:14 +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=1739450057; cv=none; b=lo0erzQbzKzvdvqOspHC0JcX6qtjRmJ09Uc0LuB/u3XPunqfvnTQZCOkgypSeeMw9sfkuail2DC1ExUff6nCMmaILptbBJGeGLs/5u5fG09s0Y05j54bkEPyXP6tsFSsfZV3xMK2wHz4bG1hANDETWZZX7LCSeQR4pXLCzZwvQg= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1739450057; c=relaxed/simple; bh=Rlklv7dis1m5I3+W2vsCMfTfiQ0cg681MxJRqeW4QvU=; h=Message-ID:Subject:From:To:Cc:Date:In-Reply-To:References: Content-Type:MIME-Version; b=tHyfbUjshdc3jggiynuK+6pYx/emZxI3WNe72VXhhPLsRwbZiIO+FYqrnMhxPfBuAsbygRk7sNLZYUDB47W/+EDDpN9aJoly4yVoeP7Mrw6AXr2jlt1KSMIEoFZAru8UP7Wu0hANrpsXnU5Yx1GPb2yMCLHdgJRPCPyHTkrf8JI= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=cLZdKOKB; 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="cLZdKOKB" Received: by smtp.kernel.org (Postfix) with ESMTPSA id A3735C4CED1; Thu, 13 Feb 2025 12:34:13 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1739450054; bh=Rlklv7dis1m5I3+W2vsCMfTfiQ0cg681MxJRqeW4QvU=; h=Subject:From:To:Cc:Date:In-Reply-To:References:From; b=cLZdKOKBFNVZDAzdBU9llTQQ4nFYOOwjzmQ4Y7cqxqY4bBuoMZ7FAkY7BrKV/agF0 Usg3I/tE4r2J36IPcXL+SPgCppdnZKT6ePqOLoRJhNZFElwmKpWSfW8+iLwZaToDzV DMFo2UX2obhBbxjqO9T7KeX3k27CXf7HmjvZOCxUefAzOsrGZVNEDvDxcu33VQGowN 9xDCw8dBMxbLfXH7M40rwxXGZ3+G4w4WGK+3y6tq+BK29ihz5qeR8qe2UPUAJSdcPU 8f+Q7+ILG0hworDhAcDNkEFH9hlk3q3BsZZzGoaWg40VztYAQ2X31MZ7kVwev2zIcW aRGlImqAOg6Hw== Message-ID: Subject: Re: [PATCH] nfsd: put dl_stid if fail to queue dl_recall From: Jeff Layton To: Li Lingfeng , chuck.lever@oracle.com, neilb@suse.de, okorniev@redhat.com, Dai.Ngo@oracle.com, tom@talpey.com, linux-nfs@vger.kernel.org, linux-kernel@vger.kernel.org Cc: yukuai1@huaweicloud.com, houtao1@huawei.com, yi.zhang@huawei.com, yangerkun@huawei.com, lilingfeng@huaweicloud.com Date: Thu, 13 Feb 2025 07:34:12 -0500 In-Reply-To: References: <20250213072536.69986-1-lilingfeng3@huawei.com> <7df4de2bff617dc5c2bb482df6dbc5ef21ba0d01.camel@kernel.org> Autocrypt: addr=jlayton@kernel.org; prefer-encrypt=mutual; keydata=mQINBE6V0TwBEADXhJg7s8wFDwBMEvn0qyhAnzFLTOCHooMZyx7XO7dAiIhDSi7G1NPxw n8jdFUQMCR/GlpozMFlSFiZXiObE7sef9rTtM68ukUyZM4pJ9l0KjQNgDJ6Fr342Htkjxu/kFV1Wv egyjnSsFt7EGoDjdKqr1TS9syJYFjagYtvWk/UfHlW09X+jOh4vYtfX7iYSx/NfqV3W1D7EDi0PqV 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Thu, 2025-02-13 at 20:28 +0800, Li Lingfeng wrote: > =E5=9C=A8 2025/2/13 19:49, Jeff Layton =E5=86=99=E9=81=93: > > On Thu, 2025-02-13 at 15:25 +0800, Li Lingfeng wrote: > > > Before calling nfsd4_run_cb to queue dl_recall to the callback_wq, we > > > increment the reference count of dl_stid. > > > We expect that after the corresponding work_struct is processed, the > > > reference count of dl_stid will be decremented through the callback > > > function nfsd4_cb_recall_release. > > > However, if the call to nfsd4_run_cb fails, the incremented reference > > > count of dl_stid will not be decremented correspondingly, leading to = the > > > following nfs4_stid leak: > > > unreferenced object 0xffff88812067b578 (size 344): > > > comm "nfsd", pid 2761, jiffies 4295044002 (age 5541.241s) > > > hex dump (first 32 bytes): > > > 01 00 00 00 6b 6b 6b 6b b8 02 c0 e2 81 88 ff ff ....kkkk.......= . > > > 00 6b 6b 6b 6b 6b 6b 6b 00 00 00 00 ad 4e ad de .kkkkkkk.....N.= . > > > backtrace: > > > kmem_cache_alloc+0x4b9/0x700 > > > nfsd4_process_open1+0x34/0x300 > > > nfsd4_open+0x2d1/0x9d0 > > > nfsd4_proc_compound+0x7a2/0xe30 > > > nfsd_dispatch+0x241/0x3e0 > > > svc_process_common+0x5d3/0xcc0 > > > svc_process+0x2a3/0x320 > > > nfsd+0x180/0x2e0 > > > kthread+0x199/0x1d0 > > > ret_from_fork+0x30/0x50 > > > ret_from_fork_asm+0x1b/0x30 > > > unreferenced object 0xffff8881499f4d28 (size 368): > > > comm "nfsd", pid 2761, jiffies 4295044005 (age 5541.239s) > > > hex dump (first 32 bytes): > > > 01 00 00 00 00 00 00 00 30 4d 9f 49 81 88 ff ff ........0M.I...= . > > > 30 4d 9f 49 81 88 ff ff 20 00 00 00 01 00 00 00 0M.I.... ......= . > > > backtrace: > > > kmem_cache_alloc+0x4b9/0x700 > > > nfs4_alloc_stid+0x29/0x210 > > > alloc_init_deleg+0x92/0x2e0 > > > nfs4_set_delegation+0x284/0xc00 > > > nfs4_open_delegation+0x216/0x3f0 > > > nfsd4_process_open2+0x2b3/0xee0 > > > nfsd4_open+0x770/0x9d0 > > > nfsd4_proc_compound+0x7a2/0xe30 > > > nfsd_dispatch+0x241/0x3e0 > > > svc_process_common+0x5d3/0xcc0 > > > svc_process+0x2a3/0x320 > > > nfsd+0x180/0x2e0 > > > kthread+0x199/0x1d0 > > > ret_from_fork+0x30/0x50 > > > ret_from_fork_asm+0x1b/0x30 > > > Fix it by checking the result of nfsd4_run_cb and call nfs4_put_stid = if > > > fail to queue dl_recall. > > >=20 > > > Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") > > > Signed-off-by: Li Lingfeng > > > --- > > > fs/nfsd/nfs4state.c | 6 +++++- > > > 1 file changed, 5 insertions(+), 1 deletion(-) > > >=20 > > > diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c > > > index 153eeea2c7c9..0ccb87be47b7 100644 > > > --- a/fs/nfsd/nfs4state.c > > > +++ b/fs/nfsd/nfs4state.c > > > @@ -5414,6 +5414,7 @@ static const struct nfsd4_callback_ops nfsd4_cb= _recall_ops =3D { > > > =20 > > > static void nfsd_break_one_deleg(struct nfs4_delegation *dp) > > > { > > > + bool queued; > > > /* > > > * We're assuming the state code never drops its reference > > > * without first removing the lease. Since we're in this lease > > > @@ -5422,7 +5423,10 @@ static void nfsd_break_one_deleg(struct nfs4_d= elegation *dp) > > > * we know it's safe to take a reference. > > > */ > > > refcount_inc(&dp->dl_stid.sc_count); > > > - WARN_ON_ONCE(!nfsd4_run_cb(&dp->dl_recall)); > > > + queued =3D nfsd4_run_cb(&dp->dl_recall); > > > + WARN_ON_ONCE(!queued); > > > + if (!queued) > > > + nfs4_put_stid(&dp->dl_stid); > > > } > > > =20 > > > /* Called from break_lease() with flc_lock held. */ > >=20 > > Have you actually seen the WARN_ON_ONCE() pop under normal usage, or > > was the problem you reproduced done via fault injection? >=20 > Hi, >=20 > I add mdelay for cb_work before processing it and add msleep in=20 > nfs_do_return_delegation to reproduce it. >=20 > --- a/fs/nfsd/nfs4state.c > +++ b/fs/nfsd/nfs4state.c > @@ -1188,6 +1188,8 @@ alloc_init_deleg(struct nfs4_client *clp, struct= =20 > nfs4_file *fp, > =C2=A0=C2=A0=C2=A0=C2=A0 dp->dl_recalled =3D false; > =C2=A0=C2=A0=C2=A0=C2=A0 nfsd4_init_cb(&dp->dl_recall, dp->dl_stid.sc_cl= ient, > =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0= =C2=A0=C2=A0 &nfsd4_cb_recall_ops, NFSPROC4_CLNT_CB_RECALL); > +=C2=A0=C2=A0=C2=A0 dp->dl_recall.cb_work.debug_flag =3D 0x1234; > +=C2=A0=C2=A0=C2=A0 printk("%s init work func %px\n", __func__,=20 > dp->dl_recall.cb_work.func); > =C2=A0=C2=A0=C2=A0=C2=A0 get_nfs4_file(fp); > =C2=A0=C2=A0=C2=A0=C2=A0 dp->dl_stid.sc_file =3D fp; > =C2=A0=C2=A0=C2=A0=C2=A0 return dp; >=20 > --- a/kernel/workqueue.c > +++ b/kernel/workqueue.c > @@ -2708,6 +2708,12 @@ static void process_scheduled_works(struct worker= =20 > *worker) > =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0= worker->pool->watchdog_ts =3D jiffies; > =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0= first =3D false; > =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 } > +=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 if (work->debug_flag =3D=3D 0= x1234) { > +=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 print= k("%s func %px\n", __func__, work->func); > +=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 print= k("%s delay before clear pending...\n", __func__); > +=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 mdela= y(10 * 1000); > +=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 print= k("%s delay done\n", __func__); > +=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 } > =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 process_one_work(worker= , work); > =C2=A0=C2=A0=C2=A0=C2=A0 } > =C2=A0} >=20 > --- a/fs/nfs/delegation.c > +++ b/fs/nfs/delegation.c > @@ -263,6 +263,15 @@ static int nfs_do_return_delegation(struct inode=20 > *inode, struct nfs_delegation * > =C2=A0=C2=A0=C2=A0=C2=A0 const struct cred *cred; > =C2=A0=C2=A0=C2=A0=C2=A0 int res =3D 0; >=20 > +=C2=A0=C2=A0=C2=A0 printk("sleep before deleg return...\n"); > +=C2=A0=C2=A0=C2=A0 while (1) { > +=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 ifdebug(PROC) > +=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 mslee= p(10 * 1000); > +=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 else > +=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 break= ; > +=C2=A0=C2=A0=C2=A0 } > +=C2=A0=C2=A0=C2=A0 printk("sleep done\n"); > + > =C2=A0=C2=A0=C2=A0=C2=A0 if (!test_bit(NFS_DELEGATION_REVOKED, &delegati= on-flags)) { > =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 spin_lock(&delegation->= lock); > =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 cred =3D get_cred(deleg= ation->cred); >=20 > > Unfortunately, this won't work. nfsd_break_one_deleg() is called from > > the ->break_lease callback with the flc->flc_lock held, and > > nfs4_put_stid can sleep in the sc_free callbacks. >=20 > Are you referring to nfs4_free_deleg? I didn't quite see where it might= =20 > sleep. Could you please explain it to me? >=20 I stand corrected. nfs4_free_deleg() won't sleep, but nfs4_free_lock_stateid() can. In this case, you know that this is a deleg stateid, so this should actually be safe after all. If you do this though, please add a comment to nfs4_free_deleg() mentioning that it mustn't ever sleep, since it can be called from that context. --=20 Jeff Layton