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Wed, 18 Mar 2026 23:47:18 -0700 (PDT) MIME-Version: 1.0 References: <20260319034912.1894770-1-senozhatsky@chromium.org> In-Reply-To: From: Richard Chang Date: Thu, 19 Mar 2026 14:47:07 +0800 X-Gm-Features: AaiRm52xZVJx1NkWEeoXPAJia0WXKTWJiqb9srzkPoIL8aJm3hm6Kd3ZjNlT7F0 Message-ID: Subject: Re: [PATCH] zram: do not slot_free() written-back slots To: Sergey Senozhatsky Cc: Andrew Morton , Minchan Kim , Brian Geffon , linux-block@vger.kernel.org, linux-mm@kvack.org Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Rspamd-Server: rspam10 X-Rspamd-Queue-Id: 0D0BAA0005 X-Stat-Signature: nb3w9yjb57d5i51zw3p64rgt5aw34c86 X-Rspam-User: X-HE-Tag: 1773902840-76087 X-HE-Meta: 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 6lIXaj10 xSeofsxxGgKpzIecxxmqEJ6JOxHmGWr92l6EJ/09dwjVjziWLe8Lv1ncQ5+PV/SxdCpzeoT7R6K8dIjqmqtdkIaHvWazzE9pX61/CCoSXcOXvaZQOvFE/h5PLH1RadFrPHTgHcp8UM4bFn5kkToaMkl1wEzc6m/Cp+6V1x9Iwc9a/AjqXT5qI5E4W4/FvLJFCQvZfmJ5+6uhA5UaL8Fj6XbzWGVC9ELOJWa04kmCPoZ/+lKgayzgBUHYDD1O2dSnSak4h0n7xE3CLUMhLVvYmhFZsgE/cyxLBMuY6roYOI/x68jdopHzwZGj9aw== Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: I think we also need clear_slot_flag(zram, index, ZRAM_PP_SLOT) On Thu, Mar 19, 2026 at 12:06=E2=80=AFPM Sergey Senozhatsky wrote: > > As a side note: > > On (26/03/19 12:44), Sergey Senozhatsky wrote: > > - slot_free(zram, index); > [..] > > - if (huge) > > - set_slot_flag(zram, index, ZRAM_HUGE); > > Original code had a bug. slot_free() would decrement ->huge_pages, > then writeback completion would restore the HUGE flag, so when slot > would get freed for real slot_free() would decrement ->huge_pages > again, leading to underflow.