From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S967256AbdJRJiW (ORCPT ); Wed, 18 Oct 2017 05:38:22 -0400 Received: from szxga04-in.huawei.com ([45.249.212.190]:8939 "EHLO szxga04-in.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933898AbdJRJiT (ORCPT ); Wed, 18 Oct 2017 05:38:19 -0400 Subject: Re: [PATCH] mm/mempolicy: add node_empty check in SYSC_migrate_pages To: Vlastimil Babka , , , , , , References: <1508290660-60619-1-git-send-email-xieyisheng1@huawei.com> <7086c6ea-b721-684e-fe3d-ff59ae1d78ed@suse.cz> CC: , , , , Linux API From: Yisheng Xie Message-ID: <20aac66a-7252-947c-355b-6da4be671dcf@huawei.com> Date: Wed, 18 Oct 2017 17:34:15 +0800 User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:45.0) Gecko/20100101 Thunderbird/45.1.0 MIME-Version: 1.0 In-Reply-To: <7086c6ea-b721-684e-fe3d-ff59ae1d78ed@suse.cz> Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit X-Originating-IP: [10.177.29.40] X-CFilter-Loop: Reflected X-Mirapoint-Virus-RAPID-Raw: score=unknown(0), refid=str=0001.0A020204.59E720F9.0073,ss=1,re=0.000,recu=0.000,reip=0.000,cl=1,cld=1,fgs=0, ip=0.0.0.0, so=2014-11-16 11:51:01, dmn=2013-03-21 17:37:32 X-Mirapoint-Loop-Id: f0fc8f9245537aab970cb6b01b93bd52 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Vlastimil, Thanks for your comment! On 2017/10/18 15:54, Vlastimil Babka wrote: > +CC linux-api > > On 10/18/2017 03:37 AM, Yisheng Xie wrote: >> As Xiaojun reported the ltp of migrate_pages01 will failed on ARCH arm64 >> system whoes has 4 nodes[0...3], all have memory and CONFIG_NODES_SHIFT=2: >> >> migrate_pages01 0 TINFO : test_invalid_nodes >> migrate_pages01 14 TFAIL : migrate_pages_common.c:45: unexpected failure - returned value = 0, expected: -1 >> migrate_pages01 15 TFAIL : migrate_pages_common.c:55: call succeeded unexpectedly >> >> In this case the test_invalid_nodes of migrate_pages01 will call: >> SYSC_migrate_pages as: >> >> migrate_pages(0, , {0x0000000000000001}, 64, , {0x0000000000000010}, 64) = 0 > > is 64 here the maxnode parameter of migrate_pages() ? Yes, I have print it in the kernel. > >> For MAX_NUMNODES is 4, so 0x10 nodemask will tread as empty set which makes >> nodes_subset(*new, node_states[N_MEMORY]) > > According to manpage of migrate_pages: > > EINVAL The value specified by maxnode exceeds a kernel-imposed > limit. Or, old_nodes or new_nodes specifies one or more node IDs that > are greater than the maximum supported node ID. Or, none of the node > IDs specified by new_nodes are on-line and allowed by the process's > current cpuset context, or none of the specified nodes contain memory. > > if maxnode parameter is 64, but MAX_NUMNODES ("kernel-imposed limit") is > 4, we should get EINVAL just because of that. I don't see such check in > the migrate_pages implementation though. Yes, that is what manpage said, but I have a question about this: if user set maxnode exceeds a kernel-imposed and try to access node without enough privilege, which errors values we should return ? For I have seen that all of the ltp migrate_pages01 will set maxnode to 64 in my system. > But then at least the > "new_nodes specifies one or more node IDs that are greater than the > maximum supported node ID" part should trigger here, because you have > node number 8 set in the new_nodes nodemask, right? > get_nodes() should be checking this according to comment: > > /* When the user specified more nodes than supported just check > if the non supported part is all zero. */ > > Somehow that doesn't seem to work then? I think we should look into > this. Your patch may still be needed, or not, after that is resolved. OK, I will check why get_nodes do not works as it comments. Thanks Yisheng Xie > >> return true, as empty set is subset of any set. >> >> So this is a common issue which also can happens in X86_64 system eg. 8 nodes[0..7], >> all with memory and CONFIG_NODES_SHIFT=3. Fix it by adding node_empty check in >> SYSC_migrate_pages. >> >> Reported-by: Tan Xiaojun >> Signed-off-by: Yisheng Xie >> --- >> mm/mempolicy.c | 5 +++++ >> 1 file changed, 5 insertions(+) >> >> diff --git a/mm/mempolicy.c b/mm/mempolicy.c >> index a2af6d5..1dfd3cc 100644 >> --- a/mm/mempolicy.c >> +++ b/mm/mempolicy.c >> @@ -1388,6 +1388,11 @@ static int copy_nodes_to_user(unsigned long __user *mask, unsigned long maxnode, >> if (err) >> goto out; >> >> + if (nodes_empty(*new)) { >> + err = -EINVAL; >> + goto out; >> + } >> + >> /* Find the mm_struct */ >> rcu_read_lock(); >> task = pid ? find_task_by_vpid(pid) : current; >> > > > . >