From: James Smart <jsmart2021@gmail.com>
To: Duoming Zhou <duoming@zju.edu.cn>, linux-nvme@lists.infradead.org
Cc: linux-kernel@vger.kernel.org, james.smart@broadcom.com,
kbusch@kernel.org, axboe@fb.com, hch@lst.de, sagi@grimberg.me
Subject: Re: [PATCH] nvme-fc: fix sleep-in-atomic-context bug caused by nvme_fc_rcv_ls_req
Date: Sun, 2 Oct 2022 10:12:15 -0700 [thread overview]
Message-ID: <305fbf18-6759-9b00-6fc0-93a4a2e40be2@gmail.com> (raw)
In-Reply-To: <20221002001909.20070-1-duoming@zju.edu.cn>
On 10/1/2022 5:19 PM, Duoming Zhou wrote:
> The function lpfc_poll_timeout() is a timer handler that runs in an
> atomic context, but it calls "kzalloc(.., GFP_KERNEL)" that may sleep.
> As a result, the sleep-in-atomic-context bug will happen. The processes
> is shown below:
>
> lpfc_poll_timeout()
> lpfc_sli_handle_fast_ring_event()
> lpfc_sli_process_unsol_iocb()
> lpfc_complete_unsol_iocb()
> lpfc_nvme_unsol_ls_handler()
> lpfc_nvme_handle_lsreq()
> nvme_fc_rcv_ls_req()
> kzalloc(sizeof(.., GFP_KERNEL) //may sleep
>
> This patch changes the gfp_t parameter of kzalloc() from GFP_KERNEL to
> GFP_ATOMIC in order to mitigate the bug.
>
> Fixes: 14fd1e98afaf ("nvme-fc: Add Disconnect Association Rcv support")
> Signed-off-by: Duoming Zhou <duoming@zju.edu.cn>
> ---
> drivers/nvme/host/fc.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/nvme/host/fc.c b/drivers/nvme/host/fc.c
> index 127abaf9ba5..36698dfc8b3 100644
> --- a/drivers/nvme/host/fc.c
> +++ b/drivers/nvme/host/fc.c
> @@ -1754,7 +1754,7 @@ nvme_fc_rcv_ls_req(struct nvme_fc_remote_port *portptr,
> lsop = kzalloc(sizeof(*lsop) +
> sizeof(union nvmefc_ls_requests) +
> sizeof(union nvmefc_ls_responses),
> - GFP_KERNEL);
> + GFP_ATOMIC);
> if (!lsop) {
> dev_info(lport->dev,
> "RCV %s LS failed: No memory\n",
I would prefer this was fixed within lpfc rather than introducing atomic
allocations (1st in either host or target transport). It was introduced
by lpfc change in irq handling style.
-- james
-- james
next prev parent reply other threads:[~2022-10-02 17:12 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-10-02 0:19 [PATCH] nvme-fc: fix sleep-in-atomic-context bug caused by nvme_fc_rcv_ls_req Duoming Zhou
2022-10-02 17:12 ` James Smart [this message]
2022-10-03 1:50 ` duoming
2022-10-03 2:56 ` James Smart
2022-10-03 17:48 ` James Smart
2022-10-04 11:10 ` duoming
2022-10-04 13:51 ` James Smart
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