From: Minchan Kim <minchan@kernel.org>
To: Matthew Wilcox <willy@infradead.org>
Cc: Tino Lehnig <tino.lehnig@contabo.de>,
ngupta@vflare.org, linux-kernel@vger.kernel.org,
Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com>,
Andrew Morton <akpm@linux-foundation.org>
Subject: Re: Zram writeback feature unstable with heavy swap utilization - BUG: Bad page state in process...
Date: Wed, 25 Jul 2018 12:02:37 +0900 [thread overview]
Message-ID: <20180725030237.GA105976@rodete-desktop-imager.corp.google.com> (raw)
In-Reply-To: <20180725025525.GD16271@bombadil.infradead.org>
On Tue, Jul 24, 2018 at 07:55:25PM -0700, Matthew Wilcox wrote:
> On Wed, Jul 25, 2018 at 11:51:06AM +0900, Minchan Kim wrote:
> > On Tue, Jul 24, 2018 at 07:35:32PM -0700, Matthew Wilcox wrote:
> > > There is NOTHING in a union with _refcount.
> >
> > Confusing. Matthew, what am I missing?
> >
> > Before:
> >
> > counters consumes 8 bytes
> > units and _refcount consumes each 4 bytes so memory space is not overlapped.
>
> Correct. _mapcount is at offset 24, as is units. _refcount is at offset 28.
>
> > union {
> > unsigned long counters;
> > struct {
> > union {
> > atomic_t _mapcount;
> > int units; /* SLOB */
> > };
> > atomic_t _refcount;
> > };
> > };
> >
> >
> > After:
> >
> > Now, units is overlapped with _refcount and _mapcount.
>
> No. units is at offset 24, as is _mapcount. But _refcount is still at
> offset 28.
Ah, got it what you mean. Sorry for the noise, Matthew.
>
> > union {
> > unsigned long counters;
> > int units; /* SLOB */
> > struct { /* Page cache */
> > atomic_t _mapcount;
> > atomic_t _refcount;
> > };
> > };
next prev parent reply other threads:[~2018-07-25 3:02 UTC|newest]
Thread overview: 30+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-07-23 12:29 Zram writeback feature unstable with heavy swap utilization - BUG: Bad page state in process Tino Lehnig
2018-07-24 1:03 ` Minchan Kim
2018-07-24 2:53 ` Sergey Senozhatsky
2018-07-24 6:47 ` Minchan Kim
2018-07-24 7:30 ` Tino Lehnig
2018-07-25 1:32 ` Minchan Kim
2018-07-25 1:55 ` Matthew Wilcox
2018-07-25 2:16 ` Minchan Kim
2018-07-25 2:35 ` Matthew Wilcox
2018-07-25 2:51 ` Minchan Kim
2018-07-25 2:55 ` Matthew Wilcox
2018-07-25 3:02 ` Minchan Kim [this message]
2018-07-25 2:51 ` Matthew Wilcox
2018-07-25 4:07 ` Sergey Senozhatsky
2018-07-25 13:21 ` Minchan Kim
2018-07-25 15:12 ` Tino Lehnig
2018-07-26 2:03 ` Minchan Kim
2018-07-26 6:10 ` Tino Lehnig
2018-07-26 6:21 ` Minchan Kim
2018-07-26 6:34 ` Tino Lehnig
2018-07-26 10:00 ` Tino Lehnig
2018-07-26 10:30 ` Minchan Kim
2018-07-26 12:35 ` Tino Lehnig
2018-07-27 9:14 ` Minchan Kim
2018-07-27 11:00 ` Tino Lehnig
2018-07-27 12:05 ` Minchan Kim
2018-07-27 12:13 ` Tino Lehnig
2018-07-27 22:58 ` Minchan Kim
2018-07-30 6:09 ` Tino Lehnig
2018-08-02 5:15 ` Minchan Kim
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