system/linux
system/linux
1
0
Fork 0
mirror of https://github.com/torvalds/linux synced 2024-09-30 08:20:40 +00:00
Code Issues Packages Projects Releases Wiki Activity

mtd_blkdevs: avoid soft lockups with some mtd/spi devices

Browse source 
With some spi devices, the heavy cpu usage due to polling the spi
registers may lead to netdev timeouts, RCU complaints, etc. This can
be acute in the absence of CONFIG_PREEMPT. This patch allows to give
enough breathing room to avoid those incorrectly detected netdev
timeouts for example.

Example splat on 5.10.92:
[  828.399306] rcu: INFO: rcu_sched self-detected stall on CPU
...
[  828.419245] Task dump for CPU 1:
[  828.422465] task:kworker/1:1H    state:R  running task on cpu   1   stack:    0 pid:   76 ppid:     2 flags:0x0000002a
[  828.433132] Workqueue: kblockd blk_mq_run_work_fn
[  828.437820] Call trace:
...
[  828.512267]  spi_mem_exec_op+0x4d0/0xde0
[  828.516184]  spi_mem_dirmap_read+0x180/0x39c
[  828.520443]  spi_nor_read_data+0x428/0x7e8
[  828.524523]  spi_nor_read+0x154/0x214
[  828.528172]  mtd_read_oob+0x440/0x714
[  828.531815]  mtd_read+0xac/0x120
[  828.535030]  mtdblock_readsect+0x178/0x230
[  828.539102]  mtd_blktrans_work+0x9fc/0xf28
[  828.543177]  mtd_queue_rq+0x1ac/0x2e4
[  828.546827]  blk_mq_dispatch_rq_list+0x2cc/0xa44
[  828.551419]  blk_mq_do_dispatch_sched+0xb0/0x7cc
[  828.556010]  __blk_mq_sched_dispatch_requests+0x350/0x494
[  828.561372]  blk_mq_sched_dispatch_requests+0xac/0xe4
[  828.566387]  __blk_mq_run_hw_queue+0x130/0x254
[  828.570806]  blk_mq_run_work_fn+0x50/0x60
[  828.574814]  process_one_work+0x578/0xf1c
[  828.578814]  worker_thread+0x5dc/0xea0
[  828.582547]  kthread+0x270/0x2d4
[  828.585765]  ret_from_fork+0x10/0x30

Signed-off-by: David Decotigny <ddecotig@google.com>
Reviewed-by: Richard Weinberger <richard@nod.at>
Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
Link: https://lore.kernel.org/linux-mtd/20220126101120.676021-1-decot+git@google.com
This commit is contained in:
David Decotigny 2022-01-26 02:11:20 -08:00 committed by Miquel Raynal
parent 7f852ec58a
commit ca6263a0c9
1 changed files with 1 additions and 0 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

1
drivers/mtd/mtd_blkdevs.c
View file

@ -158,6 +158,7 @@ static void mtd_blktrans_work(struct mtd_blktrans_dev *dev)
}
background_done = 0;
cond_resched();
spin_lock_irq(&dev->queue_lock);
}
}