Messages in this thread | | | Date | Thu, 30 Apr 2015 14:47:02 +0900 | From | Minchan Kim <> | Subject | Re: [PATCHv3 9/9] zram: add dynamic device add/remove functionality |
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Hello Sergey,
On Wed, Apr 29, 2015 at 04:23:28PM +0900, Sergey Senozhatsky wrote: > On (04/29/15 16:02), Sergey Senozhatsky wrote: > > sure. I was talking about this one: > > > > CPU0 CPU1 > > umount > > zram_remove() > > lock ->bd_mutex > > zram_reset_device() > > unlock ->bd_mutex > > disksize_store > > mount > > echo 'test' > /mnt/test > > kfree zram > > zram write > > > > I'll take a look later today. currently I think of something like: > > > sysfs_remove_group() > lock ->bd_mutex > ... check ->bd_openers > > zram_reset_device() > blk_cleanup_queue() > del_gendisk() > put_disk() > > unlock ->bd_mutex > bdput bdev > > idr_remove() > kfree(zram) > > > iow, idr_remove() and kfree() are done outside of ->bd_mutex lock. > but I may be wrong. haven't tested yet. but seems reasonable: we > invalidate ->bdev, delete partitions, etc., holding ->bd_mutex and > then release ->bdev, which does final put. need to check that in > detail. > > -ss
Isn't it related to bd_mutex? I think the problem of deadlock is that you are trying to remove sysfs file in sysfs handler.
#> echo 1 > /sys/xxx/zram_remove
kernfs_fop_write - hold s_active -> zram_remove_store -> zram_remove -> sysfs_remove_group - hold s_active *again*
Right?
-- Kind regards, Minchan Kim
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