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[66.29.188.166]) by smtp.gmail.com with ESMTPSA id j6sm31673181pfg.126.2018.12.05.05.39.27 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Wed, 05 Dec 2018 05:39:27 -0800 (PST) Subject: Re: Kernel crashes after 529262d56dbe "block: remove ->poll_fn" From: Jens Axboe To: Kirill Tkhai , hch@lst.de, sagi@grimberg.me, linux-block@vger.kernel.org, linux-kernel@vger.kernel.org References: <0bd2d36e-bef0-b836-7039-124ae4d346a6@virtuozzo.com> <5e8d3302-a7d0-3483-6540-f0b87c237f7d@virtuozzo.com> <0e6c1e68-38b0-6618-40cd-a2b72dc4e240@kernel.dk> Message-ID: Date: Wed, 5 Dec 2018 06:39:26 -0700 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.2.1 MIME-Version: 1.0 In-Reply-To: <0e6c1e68-38b0-6618-40cd-a2b72dc4e240@kernel.dk> Content-Type: text/plain; charset=windows-1252 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-block-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org On 12/5/18 6:20 AM, Jens Axboe wrote: > On 12/5/18 6:05 AM, Kirill Tkhai wrote: >> On 05.12.2018 15:45, Jens Axboe wrote: >>> On 12/5/18 5:19 AM, Kirill Tkhai wrote: >>>> Hi, >>>> >>>> commit 529262d56dbe from today linux-next makes my kernel crash: >>>> >>>> Author: Christoph Hellwig >>>> Date: Sun Dec 2 17:46:26 2018 +0100 >>>> >>>> block: remove ->poll_fn >>>> >>>> Traceback is below, config and reproducer (not minimal, just a random one populating swap) are attached. >>>> >>>> [ 29.097612] BUG: unable to handle kernel NULL pointer dereference at 0000000000000000 >>>> [ 29.098730] #PF error: [INSTR] >>>> [ 29.099104] PGD 0 P4D 0 >>>> [ 29.099425] Oops: 0010 [#1] PREEMPT SMP >>>> [ 29.099879] CPU: 3 PID: 925 Comm: bash Not tainted 4.20.0-rc5-next-20181205+ #244 >>>> [ 29.100658] RIP: 0010: (null) >>>> [ 29.101100] Code: Bad RIP value. >>>> [ 29.101480] RSP: 0000:ffffc9000023fb80 EFLAGS: 00010202 >>>> [ 29.102061] RAX: ffffffff8182d0e0 RBX: ffff88807ceee000 RCX: 0000000000000000 >>>> [ 29.102818] RDX: ffff88807d560f40 RSI: 0000000000000000 RDI: ffff88807ceee000 >>>> [ 29.103661] RBP: 0000000000000001 R08: 0000000000000000 R09: 0000000000002000 >>>> [ 29.104560] R10: 00000000ffffffff R11: ffff88807c854150 R12: 0000000000000000 >>>> [ 29.105458] R13: 0000000000000002 R14: ffff88807d7236c0 R15: ffffc9000023fe20 >>>> [ 29.106438] FS: 00007faba91d7740(0000) GS:ffff88807db80000(0000) knlGS:0000000000000000 >>>> [ 29.107304] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 >>>> [ 29.107917] CR2: ffffffffffffffd6 CR3: 000000007a172000 CR4: 00000000000006a0 >>>> [ 29.109401] Call Trace: >>>> [ 29.110017] ? blk_poll+0x27c/0x340 >>>> [ 29.110691] ? submit_bio+0x40/0x120 >>>> [ 29.111278] ? swap_readpage+0x148/0x190 >>>> [ 29.111924] ? read_swap_cache_async+0x53/0x60 >>>> [ 29.112670] ? swap_cluster_readahead+0x231/0x2b0 >>>> [ 29.113310] ? swapin_readahead+0x2ce/0x400 >>>> [ 29.113878] ? pagecache_get_page+0x2b/0x210 >>>> [ 29.114416] ? do_swap_page+0x42c/0x800 >>>> [ 29.114919] ? __handle_mm_fault+0x544/0xdd0 >>>> [ 29.115455] ? handle_mm_fault+0x112/0x230 >>>> [ 29.115978] ? __do_page_fault+0x196/0x410 >>>> [ 29.116501] ? __put_user_4+0x19/0x20 >>>> [ 29.116990] ? page_fault+0x5/0x20 >>>> [ 29.117451] ? page_fault+0x1b/0x20 >>>> [ 29.117925] CR2: 0000000000000000 >>>> [ 29.118472] ---[ end trace 0faa4ddc190b41fa ]--- >>> >>> Can you try this? The swap read-in poll attempts looks totally >>> incorrect. >>> >>> >>> diff --git a/mm/page_io.c b/mm/page_io.c >>> index 5bdfd21c1bd9..f3455f9f8dc7 100644 >>> --- a/mm/page_io.c >>> +++ b/mm/page_io.c >>> @@ -401,6 +401,8 @@ int swap_readpage(struct page *page, bool synchronous) >>> get_task_struct(current); >>> bio->bi_private = current; >>> bio_set_op_attrs(bio, REQ_OP_READ, 0); >>> + if (synchronous) >>> + bio->bi_opf |= REQ_HIPRI; >>> count_vm_event(PSWPIN); >>> bio_get(bio); >>> qc = submit_bio(bio); >>> @@ -411,7 +413,7 @@ int swap_readpage(struct page *page, bool synchronous) >>> break; >>> >>> if (!blk_poll(disk->queue, qc, true)) >>> - break; >>> + io_schedule(); >>> } >>> __set_current_state(TASK_RUNNING); >>> bio_put(bio); >> >> Still crashes: > > What device is this? This might also help... diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h index 0b3874bdbc6a..81f1b105946b 100644 --- a/include/linux/blkdev.h +++ b/include/linux/blkdev.h @@ -606,8 +606,7 @@ struct request_queue { (1 << QUEUE_FLAG_ADD_RANDOM)) #define QUEUE_FLAG_MQ_DEFAULT ((1 << QUEUE_FLAG_IO_STAT) | \ - (1 << QUEUE_FLAG_SAME_COMP) | \ - (1 << QUEUE_FLAG_POLL)) + (1 << QUEUE_FLAG_SAME_COMP)) void blk_queue_flag_set(unsigned int flag, struct request_queue *q); void blk_queue_flag_clear(unsigned int flag, struct request_queue *q); -- Jens Axboe