From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from us-smtp-delivery-194.mimecast.com ([216.205.24.194]:35629 "EHLO us-smtp-delivery-194.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751293AbdFELso (ORCPT ); Mon, 5 Jun 2017 07:48:44 -0400 From: Trond Myklebust To: "baijiaju1990@163.com" , "anna.schumaker@netapp.com" CC: "linux-kernel@vger.kernel.org" , "linux-nfs@vger.kernel.org" Subject: Re: [PATCH] fs: nfs: Fix a sleep-in-atomic bug in nfs_access_add_cache Date: Mon, 5 Jun 2017 11:48:37 +0000 Message-ID: <1496663315.3433.1.camel@primarydata.com> References: <1496649904-1855-1-git-send-email-baijiaju1990@163.com> In-Reply-To: <1496649904-1855-1-git-send-email-baijiaju1990@163.com> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: linux-nfs-owner@vger.kernel.org List-ID: T24gTW9uLCAyMDE3LTA2LTA1IGF0IDE2OjA1ICswODAwLCBKaWEtSnUgQmFpIHdyb3RlOg0KPiBU aGUgZHJpdmVyIG1heSBzbGVlcCB1bmRlciBhIHJjdSByZWFkIGxvY2ssIGFuZCBmdW5jdGlvbiBj YWxsIHBhdGgNCj4gaXM6DQo+IG5mc19wZXJtaXNzaW9uIChhY3F1aXJlIHRoZSBsb2NrIGJ5IHJj dV9yZWFkX2xvY2spDQo+IMKgIG5mc19kb19hY2Nlc3MNCj4gwqDCoMKgwqBuZnNfYWNjZXNzX2Fk ZF9jYWNoZQ0KPiDCoMKgwqDCoMKgwqBrbWFsbG9jKEdGUF9LRVJORUwpIC0tPiBtYXkgc2xlZXAN Cj4gDQo+IFRvIGZpeCBpdCwgIkdGUF9LRVJORUwiIGlzIHJlcGxhY2VkIHdpdGggIkdGUF9BVE9N SUMiLg0KPiANCj4gU2lnbmVkLW9mZi1ieTogSmlhLUp1IEJhaSA8YmFpamlhanUxOTkwQDE2My5j b20+DQo+IC0tLQ0KPiDCoGZzL25mcy9kaXIuYyB8wqDCoMKgwqAyICstDQo+IMKgMSBmaWxlIGNo YW5nZWQsIDEgaW5zZXJ0aW9uKCspLCAxIGRlbGV0aW9uKC0pDQo+IA0KPiBkaWZmIC0tZ2l0IGEv ZnMvbmZzL2Rpci5jIGIvZnMvbmZzL2Rpci5jDQo+IGluZGV4IDMyY2NkNzcuLjdhMDc0ZGIgMTAw NjQ0DQo+IC0tLSBhL2ZzL25mcy9kaXIuYw0KPiArKysgYi9mcy9uZnMvZGlyLmMNCj4gQEAgLTIz MzMsNyArMjMzMyw3IEBAIHN0YXRpYyB2b2lkIG5mc19hY2Nlc3NfYWRkX3JidHJlZShzdHJ1Y3Qg aW5vZGUNCj4gKmlub2RlLCBzdHJ1Y3QgbmZzX2FjY2Vzc19lbnRyeSAqDQo+IMKgDQo+IMKgdm9p ZCBuZnNfYWNjZXNzX2FkZF9jYWNoZShzdHJ1Y3QgaW5vZGUgKmlub2RlLCBzdHJ1Y3QNCj4gbmZz X2FjY2Vzc19lbnRyeSAqc2V0KQ0KPiDCoHsNCj4gLQlzdHJ1Y3QgbmZzX2FjY2Vzc19lbnRyeSAq Y2FjaGUgPSBrbWFsbG9jKHNpemVvZigqY2FjaGUpLA0KPiBHRlBfS0VSTkVMKTsNCj4gKwlzdHJ1 Y3QgbmZzX2FjY2Vzc19lbnRyeSAqY2FjaGUgPSBrbWFsbG9jKHNpemVvZigqY2FjaGUpLA0KPiBH RlBfQVRPTUlDKTsNCj4gwqAJaWYgKGNhY2hlID09IE5VTEwpDQo+IMKgCQlyZXR1cm47DQo+IMKg CVJCX0NMRUFSX05PREUoJmNhY2hlLT5yYl9ub2RlKTsNCg0KVGhlIFJDVSBsb2NrZWQgY29kZXBh dGggd2lsbCBub3QgZXZlciBoaXQgbmZzX2FjY2Vzc19hZGRfcmJ0cmVlKCkuIEl0DQpyZXR1cm5z IHdpdGggYW4gZXJyb3IgY29kZSBvZiAtRUNISUxEIGFmdGVyIHRoZSB0ZXN0IG9mICJtYXlfYmxv Y2siLg0KDQpDaGVlcnMNCiAgVHJvbmQNCi0tIA0KVHJvbmQgTXlrbGVidXN0DQpMaW51eCBORlMg Y2xpZW50IG1haW50YWluZXIsIFByaW1hcnlEYXRhDQp0cm9uZC5teWtsZWJ1c3RAcHJpbWFyeWRh dGEuY29tDQo= From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751556AbdFELsq (ORCPT ); Mon, 5 Jun 2017 07:48:46 -0400 Received: from us-smtp-delivery-194.mimecast.com ([216.205.24.194]:33705 "EHLO us-smtp-delivery-194.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751335AbdFELso (ORCPT ); Mon, 5 Jun 2017 07:48:44 -0400 From: Trond Myklebust To: "baijiaju1990@163.com" , "anna.schumaker@netapp.com" CC: "linux-kernel@vger.kernel.org" , "linux-nfs@vger.kernel.org" Subject: Re: [PATCH] fs: nfs: Fix a sleep-in-atomic bug in nfs_access_add_cache Thread-Topic: [PATCH] fs: nfs: Fix a sleep-in-atomic bug in nfs_access_add_cache Thread-Index: AQHS3dIpXDpxZlvObkmGtfZIkyOg+6IWJ66A Date: Mon, 5 Jun 2017 11:48:37 +0000 Message-ID: <1496663315.3433.1.camel@primarydata.com> References: <1496649904-1855-1-git-send-email-baijiaju1990@163.com> In-Reply-To: <1496649904-1855-1-git-send-email-baijiaju1990@163.com> Accept-Language: en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: x-originating-ip: [68.49.162.121] x-ms-publictraffictype: Email x-microsoft-exchange-diagnostics: 1;MWHPR11MB1360;7:u7viuhLESXM5+YlyOwD99xEd9UHfxlVsprZUXQLQI9Hk5xbJ5zjKaZIBJMqF5Z1UYlIH5207x7GSOzSkuTTMBVql5yHh5h2yqlmMp3sp+9nXJpwzYDkg/0ZSKxQC5o4YNabXARH7nPOWT/4VOuTmC9HxXf20/HtbzxI7wq4fVGjJmy3GCTb0n1auNQWAE/CzAy7YGkBWWCo7ocxZLFp7v3RZAucFENV8Bdr1XeCAaY4j2WMSZf42vlOe7YIhv2ZlDj69Y0LDcMcied8WvlOT5ef9Q7CLE29wxlSrFOu2ycTnl3pWNl3FeQD/JFGWY3dY4viezPEYZFJ7b27JIQfSUA==;20:PPDDVzQm0deFthCXkueuNm7THu1V8L0eBdEa2opr7i/6lzkNOkIk60Cpn8E2FxDyP8nb41IO4PTYmjK9ryZT9HM6RAWI6ZNfN/qgUNoixJKebJpmqC/QwjEuFCvFy3cGNWOdVMfUyI81ExJGf1HoC5d20yzvMlyef3KeX80R6pM= x-ms-traffictypediagnostic: MWHPR11MB1360: x-ms-office365-filtering-correlation-id: 7cb92291-c73a-499e-fd37-08d4ac08cdd3 x-microsoft-antispam: UriScan:;BCL:0;PCL:0;RULEID:(22001)(2017030254075)(201703131423075)(201702281549075);SRVR:MWHPR11MB1360; 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spamdiagnosticoutput: 1:99 spamdiagnosticmetadata: NSPM Content-ID: <79C7B7B18FD4CA4CA793BBBAE5FA0754@namprd11.prod.outlook.com> MIME-Version: 1.0 X-OriginatorOrg: primarydata.com X-MS-Exchange-CrossTenant-originalarrivaltime: 05 Jun 2017 11:48:37.6989 (UTC) X-MS-Exchange-CrossTenant-fromentityheader: Hosted X-MS-Exchange-CrossTenant-id: 03193ed6-8726-4bb3-a832-18ab0d28adb7 X-MS-Exchange-Transport-CrossTenantHeadersStamped: MWHPR11MB1360 X-MC-Unique: MQnim8CnOeey1o1d6VwR4w-1 Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Transfer-Encoding: 8bit X-MIME-Autoconverted: from base64 to 8bit by mail.home.local id v55Bn2Ae027556 On Mon, 2017-06-05 at 16:05 +0800, Jia-Ju Bai wrote: > The driver may sleep under a rcu read lock, and function call path > is: > nfs_permission (acquire the lock by rcu_read_lock) >   nfs_do_access >     nfs_access_add_cache >       kmalloc(GFP_KERNEL) --> may sleep > > To fix it, "GFP_KERNEL" is replaced with "GFP_ATOMIC". > > Signed-off-by: Jia-Ju Bai > --- >  fs/nfs/dir.c |    2 +- >  1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/fs/nfs/dir.c b/fs/nfs/dir.c > index 32ccd77..7a074db 100644 > --- a/fs/nfs/dir.c > +++ b/fs/nfs/dir.c > @@ -2333,7 +2333,7 @@ static void nfs_access_add_rbtree(struct inode > *inode, struct nfs_access_entry * >   >  void nfs_access_add_cache(struct inode *inode, struct > nfs_access_entry *set) >  { > - struct nfs_access_entry *cache = kmalloc(sizeof(*cache), > GFP_KERNEL); > + struct nfs_access_entry *cache = kmalloc(sizeof(*cache), > GFP_ATOMIC); >   if (cache == NULL) >   return; >   RB_CLEAR_NODE(&cache->rb_node); The RCU locked codepath will not ever hit nfs_access_add_rbtree(). It returns with an error code of -ECHILD after the test of "may_block". Cheers Trond -- Trond Myklebust Linux NFS client maintainer, PrimaryData trond.myklebust@primarydata.com