Messages in this thread | | | From | Justin He <> | Subject | RE: [PATCH] qed: fix possible unpaired spin_{un}lock_bh in _qed_mcp_cmd_and_union() | Date | Mon, 19 Jul 2021 13:16:53 +0000 |
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Hi Prabhakar
> -----Original Message----- > From: Prabhakar Kushwaha <prabhakar.pkin@gmail.com> > Sent: Monday, July 19, 2021 6:36 PM > To: Justin He <Justin.He@arm.com> > Cc: Ariel Elior <aelior@marvell.com>; GR-everest-linux-l2@marvell.com; > David S. Miller <davem@davemloft.net>; Jakub Kicinski <kuba@kernel.org>; > netdev@vger.kernel.org; Linux Kernel Mailing List <linux- > kernel@vger.kernel.org>; nd <nd@arm.com>; Shai Malin <malin1024@gmail.com>; > Shai Malin <smalin@marvell.com>; Prabhakar Kushwaha <pkushwaha@marvell.com> > Subject: Re: [PATCH] qed: fix possible unpaired spin_{un}lock_bh in > _qed_mcp_cmd_and_union() > > Hi Jia, > > On Thu, Jul 15, 2021 at 2:28 PM Jia He <justin.he@arm.com> wrote: > > > > Liajian reported a bug_on hit on a ThunderX2 arm64 server with FastLinQ > > QL41000 ethernet controller: > > BUG: scheduling while atomic: kworker/0:4/531/0x00000200 > > [qed_probe:488()]hw prepare failed > > kernel BUG at mm/vmalloc.c:2355! > > Internal error: Oops - BUG: 0 [#1] SMP > > CPU: 0 PID: 531 Comm: kworker/0:4 Tainted: G W 5.4.0-77-generic #86- > Ubuntu > > pstate: 00400009 (nzcv daif +PAN -UAO) > > Call trace: > > vunmap+0x4c/0x50 > > iounmap+0x48/0x58 > > qed_free_pci+0x60/0x80 [qed] > > qed_probe+0x35c/0x688 [qed] > > __qede_probe+0x88/0x5c8 [qede] > > qede_probe+0x60/0xe0 [qede] > > local_pci_probe+0x48/0xa0 > > work_for_cpu_fn+0x24/0x38 > > process_one_work+0x1d0/0x468 > > worker_thread+0x238/0x4e0 > > kthread+0xf0/0x118 > > ret_from_fork+0x10/0x18 > > > > In this case, qed_hw_prepare() returns error due to hw/fw error, but in > > theory work queue should be in process context instead of interrupt. > > > > The root cause might be the unpaired spin_{un}lock_bh() in > > _qed_mcp_cmd_and_union(), which causes botton half is disabled > incorrectly. > > > > Reported-by: Lijian Zhang <Lijian.Zhang@arm.com> > > Signed-off-by: Jia He <justin.he@arm.com> > > --- > > This patch is adding additional spin_{un}lock_bh(). > Can you please enlighten about the exact flow causing this unpaired > spin_{un}lock_bh. > For instance: _qed_mcp_cmd_and_union() In while loop spin_lock_bh() qed_mcp_has_pending_cmd() (assume false), will break the loop if (cnt >= max_retries) { ... return -EAGAIN; <-- here returns -EAGAIN without invoking bh unlock }
> Also, > as per description, looks like you are not sure actual the root-cause. > does this patch really solved the problem?
I don't have that ThunderX2 to verify the patch. But I searched all the spin_lock/unlock_bh and spin_lock_irqsave/irqrestore under driver/.../qlogic, this is the only problematic point I could figure out. And this might be possible code path of qed_probe().
-- Cheers, Justin (Jia He)
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