On 08/12/2016 02:29 PM, Dan Williams wrote:
...or, for that matter, any block device driver on a bus that supports hotplug?
In 4.8 Jens merged the following fix for a crash that was triggered by
repeatedly reconfiguring a libnvdimm namespace causing it to destroy
and create disks (rapid hotplug).
df08c32ce3be block: fix bdi vs gendisk lifetime mismatch
At the time I realized that the fix only addressed block device
drivers that use a dynamic devt and theorized that we still have a
problem with static devt drivers like sd. Lo and behold Dave was
bitten by this exact scenario:
WARNING: CPU: 23 PID: 9672 at fs/sysfs/dir.c:31 sysfs_warn_dup+0x62/0x80
sysfs: cannot create duplicate filename '/devices/virtual/bdi/8:16'
[..]
CPU: 23 PID: 9672 Comm: kworker/u66:2 Tainted: G I
4.6.3-300.fc24.x86_64 #1
[ ... ]
Before spending effort trying to flush the destruction of old bdi
instances before new ones are registered, is it rather time to
complete the conversion of sd to only use dynamically allocated devt?
Hello Dan,
Sorry but I'm not familiar with dynamically allocated devt's. But I
would appreciate it if Dave could test the following patch: "Fix an sd
reregistration race, v5" (https://patchwork.kernel.org/patch/9178155/).
Thanks,
Bart.
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