>>> "Joe Jin" <joe.jin@xxxxxxxxxx> 19.01.10 15:13 >>>
>When tested continous reboot VM testcase kernel panic. then I write
>a program as blow:
>while (1) {
> open("/sys/devices/xen-backend/vbd-x-xxxx/statistics/rd_sect");
> usleep(100);
> read(fd, buff, BUFF_LEN);
>}
>
>running it, then reboot the vm, will hit the panic.
>
>As I have menthioned, when open the file, kernel have initialized
>file handler, when call file operation, call the function.
>At here, even blkback_remove() have delete sysfs entry, but did not
>released sysfs->fops, that caused the panic.
That would seem like a general sysfs problem then - I can't imagine
other modules do much to prevent this, though I'm sure there are
other modules which add/remove entries on the fly. Would require
some looking through the sources to see whether there is any
generally usable (and simple) solution to this.
But irrespective of that, I think the race remains even after your
patch - only the window gets smaller.
Jan
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