From: Michal Hocko <mhocko@suse.com>
To: kernel test robot <oliver.sang@intel.com>
Cc: Feng Tang <feng.tang@intel.com>, 0day robot <lkp@intel.com>,
LKML <linux-kernel@vger.kernel.org>,
lkp@lists.01.org, ltp@lists.linux.it, linux-mm@kvack.org,
Andrew Morton <akpm@linux-foundation.org>,
David Rientjes <rientjes@google.com>,
Dave Hansen <dave.hansen@intel.com>,
Ben Widawsky <ben.widawsky@intel.com>,
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>,
ying.huang@intel.com
Subject: Re: [mm/mempolicy] 7463fff037: ltp.mbind01.fail
Date: Mon, 7 Jun 2021 10:10:08 +0200 [thread overview]
Message-ID: <YL3UYOGIz1HoqGd1@dhcp22.suse.cz> (raw)
In-Reply-To: <20210607074815.GC16270@xsang-OptiPlex-9020>
On Mon 07-06-21 15:48:15, kernel test robot wrote:
> mbind01.c:169: TINFO: case MPOL_PREFERRED (no target)
> mbind01.c:188: TFAIL: Wrong policy: 1, expected: 4
AFAIU this points to
static void test_none(unsigned int i, char *p)
{
struct test_case *tc = &tcase[i];
TEST(mbind(p, MEM_LENGTH, tc->policy, NULL, 0, tc->flags));
}
So it calls MPOL_PREFERRED with NULL parameter and the test has failed
because the kernel returns MPOL_LOCAL instead of MPOL_PREFERRED. Strictly
speaking this is breaking user interface but I am wondering whether this
really matter or is completely unexpected. The manual page explicitly
talks about this case
"
If the nodemask and maxnode arguments specify the empty set, then
the memory is allocated on the node of the CPU that triggered the
allocation.
"
I would be inclined to keep this inconsistency and see whether anybody
actually complains and have a relevant use for this behavior. The
cleanup which makes the code easier to maintain and less error prone
doesn't really deserve to get ditched just because of this IMHO.
--
Michal Hocko
SUSE Labs
next prev parent reply other threads:[~2021-06-07 8:10 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-06-01 15:14 [v4 PATCH 0/3] mm/mempolicy: some fix and semantics cleanup Feng Tang
2021-06-01 15:14 ` [v4 PATCH 1/3] mm/mempolicy: cleanup nodemask intersection check for oom Feng Tang
2021-06-01 15:14 ` [v4 PATCH 2/3] mm/mempolicy: don't handle MPOL_LOCAL like a fake MPOL_PREFERRED policy Feng Tang
2021-06-03 7:41 ` Michal Hocko
2021-06-03 8:18 ` Feng Tang
2021-06-07 7:48 ` [mm/mempolicy] 7463fff037: ltp.mbind01.fail kernel test robot
2021-06-07 8:10 ` Michal Hocko [this message]
2021-06-01 15:14 ` [v4 PATCH 3/3] mm/mempolicy: unify the parameter sanity check for mbind and set_mempolicy Feng Tang
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