Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20;
MIME-Version: 1.0
References: <CA+G9fYsK5WUxs6p9NaE4e3p7ew_+s0SdW0+FnBgiLWdYYOvoMg@mail.gmail.com>
In-Reply-To: <CA+G9fYsK5WUxs6p9NaE4e3p7ew_+s0SdW0+FnBgiLWdYYOvoMg@mail.gmail.com>
From:   Marco Elver <elver@google.com>
Date:   Wed, 30 Nov 2022 13:54:44 +0100
Message-ID: <CANpmjNOQxZ--jXZdqN3tjKE=sd4X6mV4K-PyY40CMZuoB5vQTg@mail.gmail.com>
Subject: Re: arm64: allmodconfig: BUG: KCSAN: data-race in p9_client_cb / p9_client_rpc
To:     Naresh Kamboju <naresh.kamboju@linaro.org>
Cc:     rcu <rcu@vger.kernel.org>,
        open list <linux-kernel@vger.kernel.org>,
        kunit-dev@googlegroups.com, lkft-triage@lists.linaro.org,
        kasan-dev <kasan-dev@googlegroups.com>,
        "Paul E. McKenney" <paulmck@kernel.org>,
        Dominique Martinet <asmadeus@codewreck.org>,
        Netdev <netdev@vger.kernel.org>,
        Anders Roxell <anders.roxell@linaro.org>
Content-Type: text/plain; charset="UTF-8"
Precedence: bulk

On Wed, 30 Nov 2022 at 13:50, Naresh Kamboju <naresh.kamboju@linaro.org> wrote:
>
> [Please ignore if it is already reported, and not an expert of KCSAN]
>
> While booting arm64 with allmodconfig following kernel BUG found,
> this build is enabled with CONFIG_INIT_STACK_NONE=y

Unsure why CONFIG_INIT_STACK_NONE=y is relevant.

> [    0.000000] Booting Linux on physical CPU 0x0000000000 [0x410fd034]
> [    0.000000] Linux version 6.1.0-rc7-next-20221130 (tuxmake@tuxmake)
> (aarch64-linux-gnu-gcc (Debian 11.3.0-6) 11.3.0, GNU ld (GNU Binutils
> for Debian) 2.39) #2 SMP PREEMPT_DYNAMIC @1669786411
> [    0.000000] random: crng init done
> [    0.000000] Machine model: linux,dummy-virt
> ...
> [  424.408466] ==================================================================
> [  424.412792] BUG: KCSAN: data-race in p9_client_cb / p9_client_rpc
> [  424.416806]
> [  424.418214] write to 0xffff00000a753000 of 4 bytes by interrupt on cpu 0:
> [  424.422437]  p9_client_cb+0x84/0x100

Please always provide line numbers and kernel commit hash or tag (I
think it's next-20221130, but not entirely clear).

Then we can look at git blame of the lines and see if it's new code.

> [  424.425048]  req_done+0xfc/0x1c0
> [  424.427443]  vring_interrupt+0x174/0x1c0
> [  424.430204]  __handle_irq_event_percpu+0x2c8/0x680
> [  424.433455]  handle_irq_event+0x9c/0x180
> [  424.436187]  handle_fasteoi_irq+0x2b0/0x340
> [  424.439139]  generic_handle_domain_irq+0x78/0xc0
> [  424.442323]  __gic_handle_irq_from_irqson.isra.0+0x3d8/0x480
> [  424.446054]  gic_handle_irq+0xb4/0x100
> [  424.448663]  call_on_irq_stack+0x2c/0x38
> [  424.451443]  do_interrupt_handler+0xd0/0x140
> [  424.454452]  el1_interrupt+0x88/0xc0
> [  424.457001]  el1h_64_irq_handler+0x18/0x40
> [  424.459856]  el1h_64_irq+0x78/0x7c
> [  424.462331]  arch_local_irq_enable+0x50/0x80
> [  424.465273]  arm64_preempt_schedule_irq+0x80/0xc0
> [  424.468497]  el1_interrupt+0x90/0xc0
> [  424.471096]  el1h_64_irq_handler+0x18/0x40
> [  424.474009]  el1h_64_irq+0x78/0x7c
> [  424.476464]  __tsan_read8+0x118/0x280
> [  424.479086]  __delay+0x104/0x140
> [  424.481521]  __udelay+0x5c/0xc0
> [  424.483905]  kcsan_setup_watchpoint+0x6cc/0x7c0
> [  424.487081]  __tsan_read4+0x168/0x280
> [  424.489729]  p9_client_rpc+0x1d0/0x580
> [  424.492429]  p9_client_getattr_dotl+0xd0/0x3c0
> [  424.495457]  v9fs_inode_from_fid_dotl+0x48/0x1c0
> [  424.498602]  v9fs_vfs_lookup+0x23c/0x3c0
> [  424.501386]  __lookup_slow+0x1b0/0x240
> [  424.504056]  walk_component+0x168/0x280
> [  424.506807]  path_lookupat+0x154/0x2c0
> [  424.509489]  filename_lookup+0x160/0x2c0
> [  424.512261]  vfs_statx+0xc0/0x280
> [  424.514710]  vfs_fstatat+0x84/0x100
> [  424.517308]  __do_sys_newfstatat+0x64/0x100
> [  424.520189]  __arm64_sys_newfstatat+0x74/0xc0
> [  424.523262]  invoke_syscall+0xb0/0x1c0
> [  424.525939]  el0_svc_common.constprop.0+0x10c/0x180
> [  424.529219]  do_el0_svc+0x54/0x80
> [  424.531662]  el0_svc+0x4c/0xc0
> [  424.533944]  el0t_64_sync_handler+0xc8/0x180
> [  424.536837]  el0t_64_sync+0x1a4/0x1a8
> [  424.539436]
> [  424.540810] read to 0xffff00000a753000 of 4 bytes by task 74 on cpu 0:
> [  424.544927]  p9_client_rpc+0x1d0/0x580
> [  424.547692]  p9_client_getattr_dotl+0xd0/0x3c0
> [  424.550564]  v9fs_inode_from_fid_dotl+0x48/0x1c0
> [  424.553550]  v9fs_vfs_lookup+0x23c/0x3c0
> [  424.556144]  __lookup_slow+0x1b0/0x240
> [  424.558655]  walk_component+0x168/0x280
> [  424.561192]  path_lookupat+0x154/0x2c0
> [  424.563721]  filename_lookup+0x160/0x2c0
> [  424.566337]  vfs_statx+0xc0/0x280
> [  424.568638]  vfs_fstatat+0x84/0x100
> [  424.571051]  __do_sys_newfstatat+0x64/0x100
> [  424.573821]  __arm64_sys_newfstatat+0x74/0xc0
> [  424.576650]  invoke_syscall+0xb0/0x1c0
> [  424.579144]  el0_svc_common.constprop.0+0x10c/0x180
> [  424.582212]  do_el0_svc+0x54/0x80
> [  424.584475]  el0_svc+0x4c/0xc0
> [  424.586611]  el0t_64_sync_handler+0xc8/0x180
> [  424.589347]  el0t_64_sync+0x1a4/0x1a8
> [  424.591758]
> [  424.593045] 1 lock held by systemd-journal/74:
> [  424.595821]  #0: ffff00000a0ead88
> (&type->i_mutex_dir_key#3){++++}-{3:3}, at: walk_component+0x158/0x280
> [  424.601588] irq event stamp: 416642
> [  424.603875] hardirqs last  enabled at (416641):
> [<ffff80000a552040>] preempt_schedule_irq+0x40/0x100
> [  424.609078] hardirqs last disabled at (416642):
> [<ffff80000a5422b8>] el1_interrupt+0x78/0xc0
> [  424.613887] softirqs last  enabled at (416464):
> [<ffff800008011130>] __do_softirq+0x5b0/0x694
> [  424.618699] softirqs last disabled at (416453):
> [<ffff80000801a9b0>] ____do_softirq+0x30/0x80
> [  424.623562]
> [  424.624841] value changed: 0x00000002 -> 0x00000003
> [  424.627838]
> [  424.629117] Reported by Kernel Concurrency Sanitizer on:
> [  424.632298] CPU: 0 PID: 74 Comm: systemd-journal Tainted: G
>        T  6.1.0-rc7-next-20221130 #2
> 26b4d3787db66414ab23fce17d22967bb2169e1f
> [  424.639393] Hardware name: linux,dummy-virt (DT)
>
> Reported-by: Linux Kernel Functional Testing <lkft@linaro.org>
>
> --
> Linaro LKFT
> https://lkft.linaro.org