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[2a02:8389:41cf:e200:aa18:f9fe:f627:2a46]) by smtp.gmail.com with ESMTPSA id kf14-20020a17090776ce00b0099bd7b26639sm11333238ejc.6.2023.10.26.02.18.06 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 26 Oct 2023 02:18:06 -0700 (PDT) Message-ID: <415694cb-5041-41d7-9ff3-eb93a7730622@gmail.com> Date: Thu, 26 Oct 2023 11:18:04 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [linux-next:master] [selftests] 5b45a75377: kernel-selftests.uevent.uevent_filtering.fail To: kernel test robot Cc: oe-lkp@lists.linux.dev, lkp@intel.com, Linux Memory Management List , Shuah Khan , linux-kselftest@vger.kernel.org References: <202310261454.46082aaa-oliver.sang@intel.com> Content-Language: en-US From: Javier Carrasco In-Reply-To: <202310261454.46082aaa-oliver.sang@intel.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kselftest@vger.kernel.org Hi, On 26.10.23 09:11, kernel test robot wrote: > > > Hello, > > kernel test robot noticed "kernel-selftests.uevent.uevent_filtering.fail" on: > > commit: 5b45a753776be5d21cf395ec97e81c9187fbeaca ("selftests: uevent filtering: fix return on error in uevent_listener") > https://git.kernel.org/cgit/linux/kernel/git/next/linux-next.git master > > [test failed on linux-next/master 2030579113a1b1b5bfd7ff24c0852847836d8fd1] > > in testcase: kernel-selftests > version: kernel-selftests-x86_64-60acb023-1_20230329 > with following parameters: > > group: group-03 > > > > compiler: gcc-12 > test machine: 36 threads 1 sockets Intel(R) Core(TM) i9-10980XE CPU @ 3.00GHz (Cascade Lake) with 32G memory > > (please refer to attached dmesg/kmsg for entire log/backtrace) > > > we also noticed this issue does not always happen. as below, we saw 15 failures > out of 50 runs. however, parent keeps passing. > > > 37013b557b7f39e6 5b45a753776be5d21cf395ec97e > ---------------- --------------------------- > fail:runs %reproduction fail:runs > | | | > :50 30% 15:50 kernel-selftests.uevent.uevent_filtering.fail > > > > If you fix the issue in a separate patch/commit (i.e. not just a new version of > the same patch/commit), kindly add following tags > | Reported-by: kernel test robot > | Closes: https://lore.kernel.org/oe-lkp/202310261454.46082aaa-oliver.sang@intel.com > > > > TAP version 13 > 1..1 > # timeout set to 300 > # selftests: uevent: uevent_filtering > # TAP version 13 > # 1..1 > # # Starting 1 tests from 1 test cases. > # # RUN global.uevent_filtering ... > # add@/devices/virtual/mem/fullACTION=addDEVPATH=/devices/virtual/mem/fullSUBSYSTEM=memSYNTH_UUID=0MAJOR=1MINOR=7DEVNAME=fullDEVMODE=0666SEQNUM=3532 > # add@/devices/virtual/mem/fullACTION=addDEVPATH=/devices/virtual/mem/fullSUBSYSTEM=memSYNTH_UUID=0MAJOR=1MINOR=7DEVNAME=fullDEVMODE=0666SEQNUM=3546 > # add@/devices/virtual/mem/fullACTION=addDEVPATH=/devices/virtual/mem/fullSUBSYSTEM=memSYNTH_UUID=0MAJOR=1MINOR=7DEVNAME=fullDEVMODE=0666SEQNUM=3556 > # add@/devices/virtual/mem/fullACTION=addDEVPATH=/devices/virtual/mem/fullSUBSYSTEM=memSYNTH_UUID=0MAJOR=1MINOR=7DEVNAME=fullDEVMODE=0666SEQNUM=3585 > # add@/devices/virtual/mem/fullACTION=addDEVPATH=/devices/virtual/mem/fullSUBSYSTEM=memSYNTH_UUID=0MAJOR=1MINOR=7DEVNAME=fullDEVMODE=0666SEQNUM=3595 > # No buffer space available - Failed to receive uevent > # # uevent_filtering.c:479:uevent_filtering:Expected 0 (0) == ret (-1) > # # uevent_filtering: Test failed at step #10 > # # FAIL global.uevent_filtering > # not ok 1 global.uevent_filtering > # # FAILED: 0 / 1 tests passed. > # # Totals: pass:0 fail:1 xfail:0 xpass:0 skip:0 error:0 > not ok 1 selftests: uevent: uevent_filtering # exit=1 > > > > The kernel config and materials to reproduce are available at: > https://download.01.org/0day-ci/archive/20231026/202310261454.46082aaa-oliver.sang@intel.com > > > What is apparently happening here is that the test returns now a proper error value in the uevent_listener function. In this case recvmsg() is returning ENOBUFS - No buffer space available. This occurs because buf[_UEVENT_BUFFER_SIZE] is not big enough, being _UEVENT_BUFFER_SIZE = (2048 *2). Therefore the error is not in the fix commit as such because the error was happening and it was not returned properly (previously ret was assigned to -1 but it was not returned). The obvious fix would be a larger buffer, but when I see de definition of UEVENT_BUFFER_SIZE in kobject.h, its value is just 2048. Then I wonder why 2048 *2 was used in the first place, why that is not enough and what size is then meaningful. After a quick search I found a discussion on Bugzilla about the UEVENT_BUFFER_SIZE being resized to 4096: https://bugzilla.kernel.org/show_bug.cgi?id=207695 But apparently it has not been resized upstream. Best regards, Javier Carrasco