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/fa6045b1371eb301f392ac84adaf3ad53bb168...
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