From: Andrew Morton <akpm@linux-foundation.org>
To: Minchan Kim <minchan@kernel.org>
Cc: Seth Jennings <sjennings@variantweb.net>,
linux-kernel@vger.kernel.org, linux-mm@kvack.org,
Nitin Gupta <ngupta@vflare.org>,
Sergey Senozhatsky <sergey.senozhatsky@gmail.com>,
Dan Streetman <ddstreet@ieee.org>,
Jerome Marchand <jmarchan@redhat.com>
Subject: Re: [PATCH] zsmalloc: correct fragile [kmap|kunmap]_atomic use
Date: Tue, 18 Nov 2014 15:34:24 -0800 [thread overview]
Message-ID: <20141118153424.70899732d4ed7933892b6055@linux-foundation.org> (raw)
In-Reply-To: <20141118232139.GA7393@bbox>
On Wed, 19 Nov 2014 08:21:39 +0900 Minchan Kim <minchan@kernel.org> wrote:
> Main reason I sent the patch is I got a subtle bug when I implement
> new feature of zsmalloc(ie, compaction) due to link's mishandling
> (ie, link was over page boundary by my fault).
> Although it was totally my mistake, it took time for a while
> to find a root cause because unpredictable kmapped address should
> be unmapped so it's almost random crash.
Fair enough.
That's pretty rude behaviour from kunmap_atomic(). Unfortunately it
just doesn't have anything with which to check the address - we'd need
to create a special per-cpu array[KM_TYPE_NR] just for the purpose.
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WARNING: multiple messages have this Message-ID (diff)
From: Andrew Morton <akpm@linux-foundation.org>
To: Minchan Kim <minchan@kernel.org>
Cc: Seth Jennings <sjennings@variantweb.net>,
linux-kernel@vger.kernel.org, linux-mm@kvack.org,
Nitin Gupta <ngupta@vflare.org>,
Sergey Senozhatsky <sergey.senozhatsky@gmail.com>,
Dan Streetman <ddstreet@ieee.org>,
Jerome Marchand <jmarchan@redhat.com>
Subject: Re: [PATCH] zsmalloc: correct fragile [kmap|kunmap]_atomic use
Date: Tue, 18 Nov 2014 15:34:24 -0800 [thread overview]
Message-ID: <20141118153424.70899732d4ed7933892b6055@linux-foundation.org> (raw)
In-Reply-To: <20141118232139.GA7393@bbox>
On Wed, 19 Nov 2014 08:21:39 +0900 Minchan Kim <minchan@kernel.org> wrote:
> Main reason I sent the patch is I got a subtle bug when I implement
> new feature of zsmalloc(ie, compaction) due to link's mishandling
> (ie, link was over page boundary by my fault).
> Although it was totally my mistake, it took time for a while
> to find a root cause because unpredictable kmapped address should
> be unmapped so it's almost random crash.
Fair enough.
That's pretty rude behaviour from kunmap_atomic(). Unfortunately it
just doesn't have anything with which to check the address - we'd need
to create a special per-cpu array[KM_TYPE_NR] just for the purpose.
next prev parent reply other threads:[~2014-11-18 23:34 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-11-14 1:11 [PATCH] zsmalloc: correct fragile [kmap|kunmap]_atomic use Minchan Kim
2014-11-14 1:11 ` Minchan Kim
2014-11-14 15:07 ` Seth Jennings
2014-11-14 15:07 ` Seth Jennings
2014-11-15 13:20 ` Sergey Senozhatsky
2014-11-15 13:20 ` Sergey Senozhatsky
2014-11-18 23:01 ` Andrew Morton
2014-11-18 23:01 ` Andrew Morton
2014-11-18 23:21 ` Minchan Kim
2014-11-18 23:21 ` Minchan Kim
2014-11-18 23:34 ` Andrew Morton [this message]
2014-11-18 23:34 ` Andrew Morton
2014-11-16 11:41 ` Ganesh Mahendran
2014-11-16 11:41 ` Ganesh Mahendran
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