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Date:   Tue, 8 Nov 2022 10:05:11 +0900
From:   Sergey Senozhatsky <senozhatsky@chromium.org>
To:     Petr Vorel <pvorel@suse.cz>
Cc:     Minchan Kim <minchan@kernel.org>, ltp@lists.linux.it,
        linux-block@vger.kernel.org, linux-kernel@vger.kernel.org,
        linux-kselftest@vger.kernel.org, Nitin Gupta <ngupta@vflare.org>,
        Sergey Senozhatsky <senozhatsky@chromium.org>,
        Jens Axboe <axboe@kernel.dk>,
        OGAWA Hirofumi <hirofumi@mail.parknet.co.jp>,
        Martin Doucha <mdoucha@suse.cz>,
        Yang Xu <xuyang2018.jy@fujitsu.com>
Subject: Re: [PATCH 0/1] Possible bug in zram on ppc64le on vfat
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On (22/11/07 23:42), Petr Vorel wrote:
[..]
> 15859712        0        0 26214400   196608      242        0
> zram01 7 TINFO: /sys/block/zram1/mm_stat
> 15859712        0        0 26214400   196608      242        0
> zram01 7 TINFO: /sys/block/zram1/mm_stat
> 15859712        0        0 26214400   196608      242        0
> zram01 7 TINFO: /sys/block/zram1/mm_stat
> 15859712        0        0 26214400   196608      242        0
> zram01 7 TINFO: /sys/block/zram1/mm_stat
> 15859712        0        0 26214400   196608      242        0
> zram01 7 TINFO: /sys/block/zram1/mm_stat
> 15859712        0        0 26214400   196608      242        0
> zram01 7 TINFO: /sys/block/zram1/mm_stat
> 15859712        0        0 26214400   196608      242        0
> zram01 7 TBROK: "loop_read_mem_used_total /sys/block/zram1/mm_stat" timed out

Looking at mm_stat_show(), mem_used can be 0 when mm_stat_show() is
called on un-initialized device

---
...
        u64 orig_size, mem_used = 0;
        long max_used;
        ssize_t ret;

        memset(&pool_stats, 0x00, sizeof(struct zs_pool_stats));

        down_read(&zram->init_lock);
        if (init_done(zram)) {
                mem_used = zs_get_total_pages(zram->mem_pool);
                zs_pool_stats(zram->mem_pool, &pool_stats);
        }
...
---

Can you check if init_done() returns true in your tests?