linux-kernel - Re: next: WARNING: CPU: 0 PID: 1200 at mm/page_alloc.c:4744 __alloc

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Date:   Sun, 25 Jun 2023 15:16:54 +0000
From:   Chuck Lever III <chuck.lever@...cle.com>
To:     Geert Uytterhoeven <geert@...ux-m68k.org>
CC:     Dan Carpenter <dan.carpenter@...aro.org>,
        Naresh Kamboju <naresh.kamboju@...aro.org>,
        open list <linux-kernel@...r.kernel.org>,
        linux-mm <linux-mm@...ck.org>,
        kasan-dev <kasan-dev@...glegroups.com>,
        "kunit-dev@...glegroups.com" <kunit-dev@...glegroups.com>,
        "lkft-triage@...ts.linaro.org" <lkft-triage@...ts.linaro.org>,
        Marco Elver <elver@...gle.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Mel Gorman <mgorman@...hsingularity.net>,
        Andrey Ryabinin <aryabinin@...tuozzo.com>
Subject: Re: next: WARNING: CPU: 0 PID: 1200 at mm/page_alloc.c:4744
 __alloc_pages+0x2e8/0x3a0



> On Jun 25, 2023, at 4:46 AM, Geert Uytterhoeven <geert@...ux-m68k.org> wrote:
> 
> On Sat, May 13, 2023 at 10:54 AM Dan Carpenter <dan.carpenter@...aro.org> wrote:
>> On Fri, May 12, 2023 at 01:56:30PM +0000, Chuck Lever III wrote:
>>>> On May 12, 2023, at 6:32 AM, Dan Carpenter <dan.carpenter@...aro.org> wrote:
>>>> I'm pretty sure Chuck Lever did this intentionally, but he's not on the
>>>> CC list.  Let's add him.
>>>> 
>>>> regards,
>>>> dan carpenter
>>>> 
>>>> On Fri, May 12, 2023 at 06:15:04PM +0530, Naresh Kamboju wrote:
>>>>> Following kernel warning has been noticed on qemu-arm64 while running kunit
>>>>> tests while booting Linux 6.4.0-rc1-next-20230512 and It was started from
>>>>> 6.3.0-rc7-next-20230420.
>>>>> 
>>>>> Reported-by: Linux Kernel Functional Testing <lkft@...aro.org>
>>>>> 
>>>>> This is always reproducible on qemu-arm64, qemu-arm, qemu-x86 and qemu-i386.
>>>>> Is this expected warning as a part of kunit tests ?
>>> 
>>> Dan's correct, this Kunit test is supposed to check the
>>> behavior of the API when a too-large privsize is specified.
>>> 
>>> I'm not sure how to make this work without the superfluous
>>> warning. Would adding GFP_NOWARN to the allocation help?
>> 
>> That would silence the splat, yes.
> 
> But introduce a build failure, as GFP_NOWARN does not exist.

This is the fix that went in:

commit b21c7ba6d9a5532add3827a3b49f49cbc0cb9779
Author:     Chuck Lever <chuck.lever@...cle.com>
AuthorDate: Fri May 19 13:12:50 2023 -0400
Commit:     Jakub Kicinski <kuba@...nel.org>
CommitDate: Mon May 22 19:24:52 2023 -0700

    net/handshake: Squelch allocation warning during Kunit test

    The "handshake_req_alloc excessive privsize" kunit test is intended
    to check what happens when the maximum privsize is exceeded. The
    WARN_ON_ONCE_GFP at mm/page_alloc.c:4744 can be disabled safely for
    this test.

    Reported-by: Linux Kernel Functional Testing <lkft@...aro.org>
    Fixes: 88232ec1ec5e ("net/handshake: Add Kunit tests for the handshake consumer API")
    Signed-off-by: Chuck Lever <chuck.lever@...cle.com>
    Link: https://lore.kernel.org/r/168451636052.47152.9600443326570457947.stgit@oracle-102.nfsv4bat.org
    Signed-off-by: Jakub Kicinski <kuba@...nel.org>

diff --git a/net/handshake/handshake-test.c b/net/handshake/handshake-test.c
index e6adc5dec11a..6193e46ee6d9 100644
--- a/net/handshake/handshake-test.c
+++ b/net/handshake/handshake-test.c
@@ -102,7 +102,7 @@ struct handshake_req_alloc_test_param handshake_req_alloc_params[] = {
        {
                .desc                   = "handshake_req_alloc excessive privsize",
                .proto                  = &handshake_req_alloc_proto_6,
-               .gfp                    = GFP_KERNEL,
+               .gfp                    = GFP_KERNEL | __GFP_NOWARN,
                .expect_success         = false,
        },
        {

Is there a platform where __GPF_NOWARN is not defined?


--
Chuck Lever