From: "Aneesh Kumar K.V" <aneesh.kumar@linux.ibm.com>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: linux-mm@kvack.org, Ben Widawsky <ben.widawsky@intel.com>,
Dave Hansen <dave.hansen@linux.intel.com>,
Feng Tang <feng.tang@intel.com>, Michal Hocko <mhocko@kernel.org>,
Andrea Arcangeli <aarcange@redhat.com>,
Mel Gorman <mgorman@techsingularity.net>,
Mike Kravetz <mike.kravetz@oracle.com>,
Randy Dunlap <rdunlap@infradead.org>,
Vlastimil Babka <vbabka@suse.cz>, Andi Kleen <ak@linux.intel.com>,
Dan Williams <dan.j.williams@intel.com>,
Huang Ying <ying.huang@intel.com>,
linux-api@vger.kernel.org
Subject: Re: [PATCH v5 2/3] mm/mempolicy: add set_mempolicy_home_node syscall
Date: Wed, 01 Dec 2021 11:52:08 +0530 [thread overview]
Message-ID: <87r1awc0a7.fsf@linux.ibm.com> (raw)
In-Reply-To: <20211130190028.6644054bc7142af36ef5c648@linux-foundation.org>
Andrew Morton <akpm@linux-foundation.org> writes:
> On Tue, 30 Nov 2021 14:29:02 +0530 "Aneesh Kumar K.V" <aneesh.kumar@linux.ibm.com> wrote:
>
>> > What's the thinking here? The node can later be offlined and the
>> > kernel takes no action to reset home nodes, so why not permit setting a
>> > presently-offline node as the home node? Checking here seems rather
>> > arbitrary?
>>
>> The node online check was needed to avoid accessing
>> uninitialised pgdat structure. Such an access can result in
>> below crash
>
> Oh. This is unobvious from reading the code. Which calls for a
> comment, no?
updated
@@ -1497,6 +1498,10 @@ SYSCALL_DEFINE4(set_mempolicy_home_node, unsigned long, start, unsigned long, le
if (flags != 0)
return -EINVAL;
+ /*
+ * Check home_node is online to avoid accessing uninitialized
+ * NODE_DATA.
+ */
if (home_node >= MAX_NUMNODES || !node_online(home_node))
return -EINVAL;
next prev parent reply other threads:[~2021-12-01 6:22 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-11-16 6:42 [PATCH v5 0/3] mm: add new syscall set_mempolicy_home_node Aneesh Kumar K.V
2021-11-16 6:42 ` [PATCH v5 1/3] mm/mempolicy: use policy_node helper with MPOL_PREFERRED_MANY Aneesh Kumar K.V
2021-11-29 10:11 ` Michal Hocko
2021-11-29 10:12 ` [PATCH 4/3] mm: drop node from alloc_pages_vma Michal Hocko
2021-11-16 6:42 ` [PATCH v5 2/3] mm/mempolicy: add set_mempolicy_home_node syscall Aneesh Kumar K.V
2021-11-29 10:32 ` Michal Hocko
2021-11-29 10:46 ` Aneesh Kumar K.V
2021-11-29 12:45 ` Michal Hocko
2021-11-29 13:47 ` Aneesh Kumar K.V
2021-11-29 14:52 ` Michal Hocko
2021-11-29 14:59 ` Aneesh Kumar K.V
2021-11-29 15:19 ` Michal Hocko
2021-11-29 22:02 ` Andrew Morton
2021-11-30 8:59 ` Aneesh Kumar K.V
2021-11-30 9:59 ` Michal Hocko
2021-12-01 3:00 ` Andrew Morton
2021-12-01 6:22 ` Aneesh Kumar K.V [this message]
2021-12-01 0:47 ` Daniel Jordan
2021-12-01 6:15 ` Aneesh Kumar K.V
2021-12-01 16:22 ` Daniel Jordan
2021-11-16 6:42 ` [PATCH v5 3/3] mm/mempolicy: wire up syscall set_mempolicy_home_node Aneesh Kumar K.V
2021-11-29 8:37 ` [PATCH v5 0/3] mm: add new " Aneesh Kumar K.V
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