From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from szxga05-in.huawei.com (szxga05-in.huawei.com [45.249.212.191]) (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 9E02F21D3F9; Thu, 13 Feb 2025 12:28:07 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=45.249.212.191 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1739449690; cv=none; b=n9SEMj2lgw269b94rhAg1hAArrRdySl7vvICEGYRMPE03CbCz84zMoNwhiNcdYrk6D7v15Ssp3K+W4csyYOHymJfvWXWt1jE0AyNokNJ5Od2p+VxkeCBGeIph5G9p+ekFkCX36XMVtQ/3z61U2eJbFdyNRS6BKSboHO91b6CSXE= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1739449690; c=relaxed/simple; bh=EAxsE2di2w+Suc7tMK3XIoJ7C/4rGfr/+ZDTxhdOA/k=; h=Message-ID:Date:MIME-Version:Subject:To:CC:References:From: In-Reply-To:Content-Type; b=AxUbumStcBMGH0HMEVh3LeT5OUgf+CxAheXGMmsMzp7rPzRNywFsy2c3DAEE5TjxRaXt+fYgaFTuOXJ8T4hQjPl84T9+ovOLRo1NYh0y/ZQ/BwIX036qDRjVFnmcb22A8fWi35t9zEDctl8r9c8ypzvcJF9RrtHSn/wxgxTngCY= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=huawei.com; spf=pass smtp.mailfrom=huawei.com; arc=none smtp.client-ip=45.249.212.191 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=huawei.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=huawei.com Received: from mail.maildlp.com (unknown [172.19.88.163]) by szxga05-in.huawei.com (SkyGuard) with ESMTP id 4YtvW50wk7z1ltXT; Thu, 13 Feb 2025 20:24:17 +0800 (CST) Received: from kwepemg500017.china.huawei.com (unknown [7.202.181.81]) by mail.maildlp.com (Postfix) with ESMTPS id 2EEE2180214; Thu, 13 Feb 2025 20:28:04 +0800 (CST) Received: from [10.174.179.155] (10.174.179.155) by kwepemg500017.china.huawei.com (7.202.181.81) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.1544.11; Thu, 13 Feb 2025 20:28:03 +0800 Message-ID: Date: Thu, 13 Feb 2025 20:28:02 +0800 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: =?UTF-8?B?TW96aWxsYSBUaHVuZGVyYmlyZCDmtYvor5XniYg=?= Subject: Re: [PATCH] nfsd: put dl_stid if fail to queue dl_recall To: Jeff Layton , , , , , , , CC: , , , , References: <20250213072536.69986-1-lilingfeng3@huawei.com> <7df4de2bff617dc5c2bb482df6dbc5ef21ba0d01.camel@kernel.org> From: Li Lingfeng In-Reply-To: <7df4de2bff617dc5c2bb482df6dbc5ef21ba0d01.camel@kernel.org> Content-Type: text/plain; charset="UTF-8"; format=flowed Content-Transfer-Encoding: 8bit X-ClientProxiedBy: dggems703-chm.china.huawei.com (10.3.19.180) To kwepemg500017.china.huawei.com (7.202.181.81) 在 2025/2/13 19:49, Jeff Layton 写道: > 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. >> >> Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") >> Signed-off-by: Li Lingfeng >> --- >> fs/nfsd/nfs4state.c | 6 +++++- >> 1 file changed, 5 insertions(+), 1 deletion(-) >> >> 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 = { >> >> 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_delegation *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 = nfsd4_run_cb(&dp->dl_recall); >> + WARN_ON_ONCE(!queued); >> + if (!queued) >> + nfs4_put_stid(&dp->dl_stid); >> } >> >> /* Called from break_lease() with flc_lock held. */ > > Have you actually seen the WARN_ON_ONCE() pop under normal usage, or > was the problem you reproduced done via fault injection? Hi, I add mdelay for cb_work before processing it and add msleep in nfs_do_return_delegation to reproduce it. --- a/fs/nfsd/nfs4state.c +++ b/fs/nfsd/nfs4state.c @@ -1188,6 +1188,8 @@ alloc_init_deleg(struct nfs4_client *clp, struct nfs4_file *fp,      dp->dl_recalled = false;      nfsd4_init_cb(&dp->dl_recall, dp->dl_stid.sc_client,                &nfsd4_cb_recall_ops, NFSPROC4_CLNT_CB_RECALL); +    dp->dl_recall.cb_work.debug_flag = 0x1234; +    printk("%s init work func %px\n", __func__, dp->dl_recall.cb_work.func);      get_nfs4_file(fp);      dp->dl_stid.sc_file = fp;      return dp; --- a/kernel/workqueue.c +++ b/kernel/workqueue.c @@ -2708,6 +2708,12 @@ static void process_scheduled_works(struct worker *worker)              worker->pool->watchdog_ts = jiffies;              first = false;          } +        if (work->debug_flag == 0x1234) { +            printk("%s func %px\n", __func__, work->func); +            printk("%s delay before clear pending...\n", __func__); +            mdelay(10 * 1000); +            printk("%s delay done\n", __func__); +        }          process_one_work(worker, work);      }  } --- a/fs/nfs/delegation.c +++ b/fs/nfs/delegation.c @@ -263,6 +263,15 @@ static int nfs_do_return_delegation(struct inode *inode, struct nfs_delegation *      const struct cred *cred;      int res = 0; +    printk("sleep before deleg return...\n"); +    while (1) { +        ifdebug(PROC) +            msleep(10 * 1000); +        else +            break; +    } +    printk("sleep done\n"); +      if (!test_bit(NFS_DELEGATION_REVOKED, &delegation->flags)) {          spin_lock(&delegation->lock);          cred = get_cred(delegation->cred); > 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. Are you referring to nfs4_free_deleg? I didn't quite see where it might sleep. Could you please explain it to me? Thanks.