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Tue, 30 Jun 2026 22:57:19 -0700 (PDT) Received: from google.com ([2a00:79e0:2031:6:faee:2436:3347:c0a2]) by smtp.gmail.com with ESMTPSA id 41be03b00d2f7-c9bbf95b8a4sm2538629a12.18.2026.06.30.22.57.17 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 30 Jun 2026 22:57:18 -0700 (PDT) Date: Wed, 1 Jul 2026 14:57:15 +0900 From: Sergey Senozhatsky To: Greg KH Cc: Sergey Senozhatsky , Oliver Neukum , Alan Stern , linux-usb@vger.kernel.org, linux-scsi@vger.kernel.org, usb-storage@lists.one-eyed-alien.net, linux-kernel@vger.kernel.org, Tomasz Figa Subject: Re: [RFC PATCH] usb: storage: uas: limit consecutive device resets in error handling Message-ID: References: <20260701040335.810297-1-senozhatsky@chromium.org> <2026070157-stench-shabby-2519@gregkh> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <2026070157-stench-shabby-2519@gregkh> On (26/07/01 07:38), Greg KH wrote: > > +static int uas_reset_limit = 3; This obviously wanted to be 0 by default (just a side note). > > +module_param_named(reset_limit, uas_reset_limit, int, 0644); > > +MODULE_PARM_DESC(reset_limit, "Maximum number of consecutive device resets during error handling before failing"); > > This is not the 1990's, we do not add module parameters for issues that > should be properly solved either automatically, or on a per-device > basis. > > There's no way that ChromeOs wants to attempt to track this module > parameter as a bootline config option, right? Can you please elaborate on "properly solved either automatically, or on a per-device basis". I don't know how to break that endless reset loop otherwise. I'm open to any suggestions, the patch is RFC for a reason. That reset loop essentially panics the system (we have hung-task watchdog and hung-task panic enabled). The kernel does uas_eh_device_reset_handler() every 30 seconds (which succeeds), while the block layer doesn't make progress and keeps the tasks blocked, which eventually triggers the watchdog: [..] <6>[ 917.070222] sd 0:0:0:0: [sda] tag#3 uas_eh_abort_handler 0 uas-tag 3 inflight: CMD IN <6>[ 917.070318] sd 0:0:0:0: [sda] tag#3 CDB: Read(10) 28 00 00 00 00 00 00 00 20 00 <6>[ 917.079434] scsi host0: uas_eh_device_reset_handler start <6>[ 917.079994] sd 0:0:0:0: [sda] tag#1 uas_zap_pending 0 uas-tag 1 inflight: CMD <6>[ 917.080046] sd 0:0:0:0: [sda] tag#1 CDB: Write(10) 2a 00 00 d3 98 08 00 04 00 00 <6>[ 917.080072] sd 0:0:0:0: [sda] tag#2 uas_zap_pending 0 uas-tag 2 inflight: CMD <6>[ 917.080118] sd 0:0:0:0: [sda] tag#2 CDB: Write(10) 2a 00 00 d3 9c 08 00 04 00 00 <6>[ 917.145714] usb 2-1.3: reset SuperSpeed Plus Gen 2x1 USB device number 4 using xhci_hcd <6>[ 917.164988] scsi host0: uas_eh_device_reset_handler success <6>[ 917.165155] sd 0:0:0:0: [sda] tag#3 FAILED Result: hostbyte=DID_ERROR driverbyte=DRIVER_OK cmd_age=30s <6>[ 917.165210] sd 0:0:0:0: [sda] tag#3 CDB: Read(10) 28 00 00 00 00 00 00 00 20 00 <3>[ 917.165239] I/O error, dev sda, sector 0 op 0x0:(READ) flags 0x80700 phys_seg 4 prio class 3 <4>[ 934.971114] rq: tag=0 hctx=0 op=WRITE sector=13867016 len=524288 age=78231 ms pid=11900 comm=image_burner state=D <4>[ 934.971169] rq: tag=1 hctx=0 op=WRITE sector=13868040 len=524288 age=78230 ms pid=11900 comm=image_burner state=D <4>[ 934.971217] blk: queue stall on sda: 3 inflight, 2 stalled (threshold 60000 ms) <6>[ 947.276222] sd 0:0:0:0: [sda] tag#3 uas_eh_abort_handler 0 uas-tag 3 inflight: CMD IN <6>[ 947.276282] sd 0:0:0:0: [sda] tag#3 CDB: Read(10) 28 00 00 00 00 00 00 00 08 00 <6>[ 947.280489] scsi host0: uas_eh_device_reset_handler start <6>[ 947.281255] sd 0:0:0:0: [sda] tag#0 uas_zap_pending 0 uas-tag 1 inflight: CMD <6>[ 947.281309] sd 0:0:0:0: [sda] tag#0 CDB: Write(10) 2a 00 00 d3 98 08 00 04 00 00 <6>[ 947.281391] sd 0:0:0:0: [sda] tag#1 uas_zap_pending 0 uas-tag 2 inflight: CMD <6>[ 947.281468] sd 0:0:0:0: [sda] tag#1 CDB: Write(10) 2a 00 00 d3 9c 08 00 04 00 00 <6>[ 947.346666] usb 2-1.3: reset SuperSpeed Plus Gen 2x1 USB device number 4 using xhci_hcd <6>[ 947.365031] scsi host0: uas_eh_device_reset_handler success <6>[ 977.479406] scsi host0: uas_eh_device_reset_handler start <6>[ 977.479963] sd 0:0:0:0: [sda] tag#2 uas_zap_pending 0 uas-tag 1 inflight: CMD <6>[ 977.480015] sd 0:0:0:0: [sda] tag#2 CDB: Write(10) 2a 00 00 d3 98 08 00 04 00 00 <6>[ 977.480042] sd 0:0:0:0: [sda] tag#3 uas_zap_pending 0 uas-tag 2 inflight: CMD <6>[ 977.480089] sd 0:0:0:0: [sda] tag#3 CDB: Write(10) 2a 00 00 d3 9c 08 00 04 00 00 <6>[ 977.480137] sd 0:0:0:0: [sda] tag#4 uas_zap_pending 0 uas-tag 3 inflight: CMD <6>[ 977.480166] sd 0:0:0:0: [sda] tag#4 CDB: Read(10) 28 00 00 00 00 00 00 00 08 00 <6>[ 977.545653] usb 2-1.3: reset SuperSpeed Plus Gen 2x1 USB device number 4 using xhci_hcd <6>[ 977.565338] scsi host0: uas_eh_device_reset_handler success <3>[ 984.123394] INFO: task image_burner:11900 blocked for more than 122 seconds. <3>[ 984.123501] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. <6>[ 984.123517] task:image_burner state:D stack:0 pid:11900 ppid:11893 flags:0x00004002 <6>[ 984.123577] Call Trace: <6>[ 984.123603] <6>[ 984.123659] __schedule+0x5e8/0x14c0 <6>[ 984.123688] ? free_unref_page_list+0x25d/0x290 <6>[ 984.123715] ? lru_gen_update_size+0x1e3/0x220 <6>[ 984.123763] schedule+0x5e/0xa0 <6>[ 984.123788] io_schedule+0x47/0x70 <6>[ 984.123814] folio_wait_bit_common+0x18a/0x270 <6>[ 984.123863] ? __pfx_wake_page_function+0x10/0x10 <6>[ 984.123889] folio_wait_writeback+0x35/0x90 <6>[ 984.123937] __filemap_fdatawait_range+0x162/0x190 <6>[ 984.123965] file_write_and_wait_range+0xa3/0x120 <6>[ 984.124013] blkdev_fsync+0x39/0x60 <6>[ 984.124040] __x64_sys_fdatasync+0x4c/0x90 <6>[ 984.124067] do_syscall_64+0x6b/0xa0