Re: [PATCH v8 11/12] zram: fix crashes with cpu hotplug multistate
From: Ming Lei <hidden>
Date: 2021-10-19 16:30:43
Also in:
linux-block, linux-fsdevel, linux-kselftest, lkml
Subsystem:
block layer, the rest, zram compressed ram block device drvier · Maintainers:
Jens Axboe, Linus Torvalds, Minchan Kim, Sergey Senozhatsky
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:quoted
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,
--
Ming