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Mon, 03 Oct 2022 10:48:34 -0700 (PDT) Message-ID: <8aeea62b-c947-6414-bca1-3bd3f427cd56@gmail.com> Date: Mon, 3 Oct 2022 10:48:31 -0700 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:102.0) Gecko/20100101 Thunderbird/102.3.0 Subject: Re: [PATCH] nvme-fc: fix sleep-in-atomic-context bug caused by nvme_fc_rcv_ls_req Content-Language: en-US To: duoming@zju.edu.cn Cc: linux-nvme@lists.infradead.org, linux-kernel@vger.kernel.org, james.smart@broadcom.com, kbusch@kernel.org, axboe@fb.com, hch@lst.de, sagi@grimberg.me References: <20221002001909.20070-1-duoming@zju.edu.cn> <305fbf18-6759-9b00-6fc0-93a4a2e40be2@gmail.com> <7bd9e071.1063f1.1839b89cefa.Coremail.duoming@zju.edu.cn> <2f36fa52-2dc3-21f3-b53c-d0a9186c3ceb@gmail.com> From: James Smart In-Reply-To: <2f36fa52-2dc3-21f3-b53c-d0a9186c3ceb@gmail.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20221003_104837_770036_05D16D86 X-CRM114-Status: GOOD ( 21.60 ) X-BeenThere: linux-nvme@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "Linux-nvme" Errors-To: linux-nvme-bounces+linux-nvme=archiver.kernel.org@lists.infradead.org On 10/2/2022 7:56 PM, James Smart wrote: > On 10/2/2022 6:50 PM, duoming@zju.edu.cn wrote: >> Hello, >> >> On Sun, 2 Oct 2022 10:12:15 -0700 James Smart wrote: >> >>> 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 >>>> --- >>>>    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. >> >> Thank your for your reply and suggestions! >> >> Do you think change the lpfc_poll_timeout() to a delayed_work is better? >> >> Best regards, >> Duoming Zhou > > as a minimum: the lpfc_complete_unsol_iocb handler should be passing off > the iocb to a work queue routine - so that the context changes so that > either nvme host or nvmet ls callback routines can be called. If > possible, it should do the axchg alloc - to avoid a GFP_ATOMIC there as > well... > > It's usually best for these nvme LS's and ELS's to be done in a slow > path thread/work queue element. That may mean segmenting a little > earlier in the path. > > -- james > looking further... lpfc_poll_timeout() should only be used on an SLI-3 adapter. The existing SLI-3 adapters don't support NVMe. So I'm a little confused by this stack trace. Can you describe what the system config/software setup is and specifically what lpfc adapter is being used (dmesg attachment logs are sufficient, or lspci output). -- james