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Dietmar Eggemann , anna-maria@linutronix.de, linux-kernel@vger.kernel.org, mingo@kernel.org, syzkaller-bugs@googlegroups.com, tglx@linutronix.de, longman@redhat.com Subject: Re: [syzbot] [kernel?] WARNING in task_work_add Message-ID: <20241022190855.GA9657@noisy.programming.kicks-ass.net> References: <6717300e.050a0220.1e4b4d.006e.GAE@google.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: On Tue, Oct 22, 2024 at 04:06:47PM +0200, Frederic Weisbecker wrote: > Adding scheduler people in Cc. > > Thanks. > > Le Mon, Oct 21, 2024 at 09:54:38PM -0700, syzbot a écrit : > > Hello, > > > > syzbot found the following issue on: > > > > HEAD commit: 9ec59cb3edc7 KVM: arm64: Shave a few bytes from the EL2 id.. > > git tree: git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-kernelci > > console output: https://syzkaller.appspot.com/x/log.txt?x=17061430580000 > > kernel config: https://syzkaller.appspot.com/x/.config?x=c154e2d4db830898 > > dashboard link: https://syzkaller.appspot.com/bug?extid=4abde9163a953b8a0fd0 > > compiler: Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40 > > userspace arch: arm64 > > > > Unfortunately, I don't have any reproducer for this issue yet. > > > > Downloadable assets: > > disk image: https://storage.googleapis.com/syzbot-assets/fc9a7d36d46a/disk-9ec59cb3.raw.xz > > vmlinux: https://storage.googleapis.com/syzbot-assets/30547ddd681e/vmlinux-9ec59cb3.xz > > kernel image: https://storage.googleapis.com/syzbot-assets/5c4e02d0f97a/Image-9ec59cb3.gz.xz > > > > IMPORTANT: if you fix the issue, please add the following tag to the commit: > > Reported-by: syzbot+4abde9163a953b8a0fd0@syzkaller.appspotmail.com > > > > ------------[ cut here ]------------ > > WARNING: CPU: 1 PID: 1 at arch/arm64/kernel/stacktrace.c:223 kunwind_next_frame_record_meta arch/arm64/kernel/stacktrace.c:216 [inline] > > WARNING: CPU: 1 PID: 1 at arch/arm64/kernel/stacktrace.c:223 kunwind_next_frame_record arch/arm64/kernel/stacktrace.c:248 [inline] > > WARNING: CPU: 1 PID: 1 at arch/arm64/kernel/stacktrace.c:223 kunwind_next arch/arm64/kernel/stacktrace.c:278 [inline] > > WARNING: CPU: 1 PID: 1 at arch/arm64/kernel/stacktrace.c:223 do_kunwind arch/arm64/kernel/stacktrace.c:309 [inline] > > WARNING: CPU: 1 PID: 1 at arch/arm64/kernel/stacktrace.c:223 kunwind_stack_walk arch/arm64/kernel/stacktrace.c:380 [inline] > > WARNING: CPU: 1 PID: 1 at arch/arm64/kernel/stacktrace.c:223 arch_stack_walk+0x458/0x48c arch/arm64/kernel/stacktrace.c:404 > > Modules linked in: > > CPU: 1 UID: 0 PID: 1 Comm: init Not tainted 6.12.0-rc3-syzkaller-g9ec59cb3edc7 #0 > > Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/13/2024 > > pstate: 804000c5 (Nzcv daIF +PAN -UAO -TCO -DIT -SSBS BTYPE=--) > > pc : kunwind_next_frame_record_meta arch/arm64/kernel/stacktrace.c:216 [inline] > > pc : kunwind_next_frame_record arch/arm64/kernel/stacktrace.c:248 [inline] > > pc : kunwind_next arch/arm64/kernel/stacktrace.c:278 [inline] > > pc : do_kunwind arch/arm64/kernel/stacktrace.c:309 [inline] > > pc : kunwind_stack_walk arch/arm64/kernel/stacktrace.c:380 [inline] > > pc : arch_stack_walk+0x458/0x48c arch/arm64/kernel/stacktrace.c:404 > > lr : 0x0 > > sp : ffff8000800176a0 > > x29: ffff800080017750 x28: 1ffff00010002f58 x27: 00000000ffff8d68 > > x26: dfff800000000000 x25: ffff0000c2c588c0 x24: dfff800000000000 > > x23: ffff700010002ef0 x22: ffff800080017850 x21: ffff8000800176b8 > > x20: ffff800080462114 x19: ffff8000800177a0 x18: dfff800000000000 > > x17: ffff800123f21000 x16: ffff80008b490b1c x15: 0000000000000001 > > x14: 1fffe000366c806a x13: ffff800097807ff0 x12: ffff800097808000 > > x11: 0000000000000000 x10: ffff0000c1978000 x9 : ffff800097807e9f > > x8 : ffff800097807fd8 x7 : 0000000000000000 x6 : 000000000000003f > > x5 : 0000000000000040 x4 : fffffffffffffff0 x3 : 0000000000000000 > > x2 : ffff0000c1978000 x1 : ffff800080029c40 x0 : 0000000000000001 > > Call trace: > > kunwind_next_frame_record_meta arch/arm64/kernel/stacktrace.c:216 [inline] (P) > > kunwind_next_frame_record arch/arm64/kernel/stacktrace.c:248 [inline] (P) > > kunwind_next arch/arm64/kernel/stacktrace.c:278 [inline] (P) > > do_kunwind arch/arm64/kernel/stacktrace.c:309 [inline] (P) > > kunwind_stack_walk arch/arm64/kernel/stacktrace.c:380 [inline] (P) > > arch_stack_walk+0x458/0x48c arch/arm64/kernel/stacktrace.c:404 (P) > > 0x0 (L) > > stack_trace_save+0xfc/0x1a0 kernel/stacktrace.c:122 > > kasan_save_stack+0x40/0x6c mm/kasan/common.c:47 > > __kasan_record_aux_stack+0xd0/0xec mm/kasan/generic.c:541 > > kasan_record_aux_stack+0x14/0x20 mm/kasan/generic.c:546 > > task_work_add+0xb8/0x464 kernel/task_work.c:66 > > task_tick_mm_cid kernel/sched/core.c:10468 [inline] > > sched_tick+0x2a8/0x404 kernel/sched/core.c:5605 I'm guessing this is very close to what 73ab05aa46b0 ("sched/core: Disable page allocation in task_tick_mm_cid()") does. Initial version of that patch was more aggressive and killed off the whole KASAN thing instead of just the page-alloc. Is that what is needed here? I'm very glad to shoot that stuff in the head.