From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id A7E02359A91; Mon, 2 Mar 2026 10:50:55 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1772448655; cv=none; b=Bo8IFQdevt9Pzz2n5jeEHvigYNHvDZwjNL6B31HiPudYuWBXbVvj2FCBcWh/j6SeeTk7NyedhoCqMxeoeki7JhuMdevtVlGIrbAclriMKF0oVdfwWqK6Aw0ibqAPbiYuuWmE/EmQ3k01MA9+DSSKQDbgOfbeYd927oQlibf0wjg= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1772448655; c=relaxed/simple; bh=ooCwVMtMeof9eUg55NNUtPSMrUI5IYvsBBfPpUNmiu8=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=B5g6ZjRLTkK1JpZiMOxJnYoWE3+rnnRCZP48h5d3MsubkLNr1ndsAED8vnphWkqwDgUnEFbDvCGbkymRrXmBvo7OA+Zl/vcjqv3m4Fiwb8bBoOWh+PJfHTWMAkXcRXO1XDS3PTKKRZPRwpJjZgUlM4fQQaGjyW6TlwaAwHfcgT4= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=fHKvAGlV; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="fHKvAGlV" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 63631C19423; Mon, 2 Mar 2026 10:50:54 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1772448655; bh=ooCwVMtMeof9eUg55NNUtPSMrUI5IYvsBBfPpUNmiu8=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=fHKvAGlV1PYQM4oFzHWWPRF/Yv3lsn7pHbcI4wEPesGHyt//zusRP7n9wglL7LoOI ZhCK58mOpx9cjjpITbEgzKyqV8Ml0pgYDx3WyVQrsAPALthSB4y74AGT934IURginD S7LDUJ/n1/2o2lmF2Tg4568RN/JKwd+ULiEM0XODU4Xm0DNwN1w3/iQQlPMhM/XO8q 9KzuIHHM1A9UUjdjpOWQ/NtY8TfKfyVjVycIgth2dFNViaI0QB3GPKr1jibnDZHDbJ uJuryc73Di6wnU+FHiy9nsYte5yb3BVgKohfue+dztdcVYxfNPAZlOKIrXGrEIlveJ xGjmTzNbjr2FA== Date: Mon, 2 Mar 2026 12:50:51 +0200 From: Leon Romanovsky To: Chaitanya Kulkarni Cc: Shinichiro Kawasaki , "linux-block@vger.kernel.org" , "linux-nvme@lists.infradead.org" , "linux-scsi@vger.kernel.org" , "nbd@other.debian.org" , "linux-rdma@vger.kernel.org" Subject: Re: blktests failures with v7.0-rc1 kernel Message-ID: <20260302105051.GP12611@unreal> References: <4c7aea9f-ae97-43c8-8b08-905696303978@nvidia.com> Precedence: bulk X-Mailing-List: linux-block@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: <4c7aea9f-ae97-43c8-8b08-905696303978@nvidia.com> On Thu, Feb 26, 2026 at 03:00:40PM +0000, Chaitanya Kulkarni wrote: > On 2/26/26 12:09 AM, Shinichiro Kawasaki wrote: > > Failure description > > =================== > > > > #1: blktrace/002 > > > > The test case blktrace/002 failed due to "BUG: using __this_cpu_read() in > > preemptible" and a following WARN [2]. > > I saw this last night it was pretty late, just glad to see simple > testcase catching bugs. > > I've a patch for this I'll send out shortly :- > > > From 6a285db1bbdbb613a85ac55a395ed2043d4eb11d Mon Sep 17 00:00:00 2001 > From: Chaitanya Kulkarni > Date: Wed, 25 Feb 2026 23:01:12 -0800 > Subject: [PATCH] blktrace: fix __this_cpu_read/write in preemptible context > > > > blktrace/002 (blktrace ftrace corruption with sysfs trace)  [failed] >     runtime  0.367s  ...  0.437s >     something found in dmesg: >     [   81.211018] run blktests blktrace/002 at 2026-02-25 22:24:33 >     [   81.239580] null_blk: disk nullb1 created >     [   81.357294] BUG: using __this_cpu_read() in preemptible > [00000000] code: dd/2516 >     [   81.362842] caller is tracing_record_cmdline+0x10/0x40 >     [   81.362872] CPU: 16 UID: 0 PID: 2516 Comm: dd Tainted: G         >        N  7.0.0-rc1lblk+ #84 PREEMPT(full) >     [   81.362877] Tainted: [N]=TEST >     [   81.362878] Hardware name: QEMU Standard PC (i440FX + PIIX, > 1996), BIOS rel-1.17.0-0-gb52ca86e094d-prebuilt.qemu.org 04/01/2014 >     [   81.362881] Call Trace: >     [   81.362884]  >     [   81.362886]  dump_stack_lvl+0x8d/0xb0 >     ... >     (See '/mnt/sda/blktests/results/nodev/blktrace/002.dmesg' for the > entire message) > > [   81.211018] run blktests blktrace/002 at 2026-02-25 22:24:33 > [   81.239580] null_blk: disk nullb1 created > [   81.357294] BUG: using __this_cpu_read() in preemptible [00000000] > code: dd/2516 > [   81.362842] caller is tracing_record_cmdline+0x10/0x40 > [   81.362872] CPU: 16 UID: 0 PID: 2516 Comm: dd Tainted: G           >  N  7.0.0-rc1lblk+ #84 PREEMPT(full) > [   81.362877] Tainted: [N]=TEST > [   81.362878] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), > BIOS rel-1.17.0-0-gb52ca86e094d-prebuilt.qemu.org 04/01/2014 > [   81.362881] Call Trace: > [   81.362884]  > [   81.362886]  dump_stack_lvl+0x8d/0xb0 > [   81.362895]  check_preemption_disabled+0xce/0xe0 > [   81.362902]  tracing_record_cmdline+0x10/0x40 > [   81.362923]  __blk_add_trace+0x307/0x5d0 > [   81.362934]  ? lock_acquire+0xe0/0x300 > [   81.362940]  ? iov_iter_extract_pages+0x101/0xa30 > [   81.362959]  blk_add_trace_bio+0x106/0x1e0 > [   81.362968]  submit_bio_noacct_nocheck+0x24b/0x3a0 > [   81.362979]  ? lockdep_init_map_type+0x58/0x260 > [   81.362988]  submit_bio_wait+0x56/0x90 > [   81.363009]  __blkdev_direct_IO_simple+0x16c/0x250 > [   81.363026]  ? __pfx_submit_bio_wait_endio+0x10/0x10 > [   81.363038]  ? rcu_read_lock_any_held+0x73/0xa0 > [   81.363051]  blkdev_read_iter+0xc1/0x140 > [   81.363059]  vfs_read+0x20b/0x330 > [   81.363083]  ksys_read+0x67/0xe0 > [   81.363090]  do_syscall_64+0xbf/0xf00 > [   81.363102]  entry_SYSCALL_64_after_hwframe+0x76/0x7e > [   81.363106] RIP: 0033:0x7f281906029d > [   81.363111] Code: 31 c0 e9 c6 fe ff ff 50 48 8d 3d 66 63 0a 00 e8 59 > ff 01 00 66 0f 1f 84 00 00 00 00 00 80 3d 41 33 0e 00 00 74 17 31 c0 0f > 05 <48> 3d 00 f0 ff ff 77 5b c3 66 2e 0f 1f 84 00 00 00 00 00 48 83 ec > [   81.363113] RSP: 002b:00007ffca127dd48 EFLAGS: 00000246 ORIG_RAX: > 0000000000000000 > [   81.363120] RAX: ffffffffffffffda RBX: 0000000000000000 RCX: > 00007f281906029d > [   81.363122] RDX: 0000000000001000 RSI: 0000559f8bfae000 RDI: > 0000000000000000 > [   81.363123] RBP: 0000000000001000 R08: 0000002863a10a81 R09: > 00007f281915f000 > [   81.363124] R10: 00007f2818f77b60 R11: 0000000000000246 R12: > 0000559f8bfae000 > [   81.363126] R13: 0000000000000000 R14: 0000000000000000 R15: > 000000000000000a > [   81.363142]  > [   81.363157] BUG: using __this_cpu_read() in preemptible [00000000] > code: dd/2516 > [   81.368486] caller is tracing_record_cmdline+0x10/0x40 > [   81.368496] CPU: 16 UID: 0 PID: 2516 Comm: dd Tainted: G           >  N  7.0.0-rc1lblk+ #84 PREEMPT(full) > [   81.368501] Tainted: [N]=TEST > [   81.368502] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), > BIOS rel-1.17.0-0-gb52ca86e094d-prebuilt.qemu.org 04/01/2014 > [   81.368503] Call Trace: > [   81.368505]  > [   81.368507]  dump_stack_lvl+0x8d/0xb0 > [   81.368513]  check_preemption_disabled+0xce/0xe0 > [   81.368518]  tracing_record_cmdline+0x10/0x40 > [   81.368523]  __blk_add_trace+0x307/0x5d0 > [   81.368528]  ? lock_acquire+0xe0/0x300 > [   81.368547]  blk_add_trace_bio+0x106/0x1e0 > [   81.368556]  blk_mq_submit_bio+0x63c/0xbb0 > [   81.368580]  __submit_bio+0xad/0x5c0 > [   81.368595]  ? submit_bio_noacct_nocheck+0x2b0/0x3a0 > [   81.368600]  submit_bio_noacct_nocheck+0x2b0/0x3a0 > [   81.368611]  submit_bio_wait+0x56/0x90 > [   81.368622]  __blkdev_direct_IO_simple+0x16c/0x250 > [   81.368635]  ? __pfx_submit_bio_wait_endio+0x10/0x10 > [   81.368656]  ? rcu_read_lock_any_held+0x73/0xa0 > [   81.368664]  blkdev_read_iter+0xc1/0x140 > [   81.368672]  vfs_read+0x20b/0x330 > [   81.368687]  ksys_read+0x67/0xe0 > [   81.368694]  do_syscall_64+0xbf/0xf00 > [   81.368702]  entry_SYSCALL_64_after_hwframe+0x76/0x7e > [   81.368705] RIP: 0033:0x7f281906029d > [   81.368708] Code: 31 c0 e9 c6 fe ff ff 50 48 8d 3d 66 63 0a 00 e8 59 > ff 01 00 66 0f 1f 84 00 00 00 00 00 80 3d 41 33 0e 00 00 74 17 31 c0 0f > 05 <48> 3d 00 f0 ff ff 77 5b c3 66 2e 0f 1f 84 00 00 00 00 00 48 83 ec > [   81.368710] RSP: 002b:00007ffca127dd48 EFLAGS: 00000246 ORIG_RAX: > 0000000000000000 > [   81.368712] RAX: ffffffffffffffda RBX: 0000000000000000 RCX: > 00007f281906029d > [   81.368713] RDX: 0000000000001000 RSI: 0000559f8bfae000 RDI: > 0000000000000000 > [   81.368714] RBP: 0000000000001000 R08: 0000002863a10a81 R09: > 00007f281915f000 > [   81.368716] R10: 00007f2818f77b60 R11: 0000000000000246 R12: > 0000559f8bfae000 > [   81.368717] R13: 0000000000000000 R14: 0000000000000000 R15: > 000000000000000a > [   81.368734]  > > The same BUG fires from blk_add_trace_plug(), blk_add_trace_unplug(), > and blk_add_trace_rq() paths as well. > > Fix by wrapping the tracing_record_cmdline() call with > preempt_disable()/preempt_enable().  This is a best-effort "record > the comm string for this PID" operation and briefly disabling > preemption around it is both safe and correct. > > With this patch now blktests for blktrace pass :- > > blktests (master) # ./check blktrace > blktrace/001 (blktrace zone management command tracing) [passed] >     runtime  3.652s  ...  3.649s > blktrace/002 (blktrace ftrace corruption with sysfs trace)  [passed] >     runtime  0.437s  ...  0.389s > blktests (master) # > > > Signed-off-by: Chaitanya Kulkarni > --- >  kernel/trace/blktrace.c | 2 ++ >  1 file changed, 2 insertions(+) > > diff --git a/kernel/trace/blktrace.c b/kernel/trace/blktrace.c > index 3b7c102a6eb3..488552036583 100644 > --- a/kernel/trace/blktrace.c > +++ b/kernel/trace/blktrace.c > @@ -383,7 +383,9 @@ static void __blk_add_trace(struct blk_trace *bt, > sector_t sector, int bytes, >      cpu = raw_smp_processor_id(); > >      if (blk_tracer) { > +        preempt_disable_notrace(); >          tracing_record_cmdline(current); > +        preempt_enable_notrace(); These lines likely belong in tracing_record_cmdline(). Thanks > >          buffer = blk_tr->array_buffer.buffer; >          trace_ctx = tracing_gen_ctx_flags(0); > -- > 2.39.5 > >