On Tue, Oct 19, 2021 at 12:36:42PM -0700, Luis Chamberlain wrote: > On Wed, Oct 20, 2021 at 12:29:53AM +0800, Ming Lei wrote: > > On Tue, Oct 19, 2021 at 08:28:21AM -0700, Luis Chamberlain wrote: > > > On Tue, Oct 19, 2021 at 10:34:41AM +0800, Ming Lei wrote: > > > > Please try the following patch against upstream(linus or next) tree(basically > > > > fold revised 2 and 3 of V1, and cover two issues: not fail zram_remove in > > > > module_exit(), race between zram_remove() and disksize_store()), and see if > > > > everything is fine for you: > > > > > > Page fault ... > > > > > > [ 18.284256] zram: Removed device: zram0 > > > [ 18.312974] BUG: unable to handle page fault for address: > > > ffffad86de903008 > > > [ 18.313707] #PF: supervisor read access in kernel mode > > > [ 18.314248] #PF: error_code(0x0000) - not-present page > > > [ 18.314797] PGD 100000067 P4D 100000067 PUD 10031e067 PMD 136a28067 > > > > That is another race between zram_reset_device() and disksize_store(), > > which is supposed to be covered by ->init_lock, and follows the delta fix > > against the last patch I posted, and the whole patch can be found in the > > github link: > > > > https://github.com/ming1/linux/commit/fa6045b1371eb301f392ac84adaf3ad53bb16894 > > > > > > diff --git a/drivers/block/zram/zram_drv.c b/drivers/block/zram/zram_drv.c > > index d0cae7a42f4d..a14ba3d350ea 100644 > > --- a/drivers/block/zram/zram_drv.c > > +++ b/drivers/block/zram/zram_drv.c > > @@ -1704,12 +1704,12 @@ static void zram_reset_device(struct zram *zram) > > set_capacity_and_notify(zram->disk, 0); > > part_stat_set_all(zram->disk->part0, 0); > > > > - up_write(&zram->init_lock); > > /* I/O operation under all of CPU are done so let's free */ > > zram_meta_free(zram, disksize); > > memset(&zram->stats, 0, sizeof(zram->stats)); > > zcomp_destroy(comp); > > reset_bdev(zram); > > + up_write(&zram->init_lock); > > } > > > > static ssize_t disksize_store(struct device *dev, > > With this, it still ends up in a state where we loop and can't get out of: > > zram: Can't change algorithm for initialized device Again, you are running two zram02.sh[1] on /dev/zram0, that isn't unexpected behavior. Here the difference is just timing. In my test VM, this message shows a while on one task, then it may be switched to another task. Just run your patches a while, nothing real difference here, and the following message can be dumped from one task for long time: can't set '107374182400' to /sys/block/zram0/disksize Also you did not answer my question about your test expected result when running the following script from two terminal concurrently: while true; do PATH=$PATH:$PWD:$PWD/../../../lib/ ./zram02.sh; done Thanks, Ming
