From: David Woodhouse <dwmw2@infradead.org>
To: "Christopher Hoover" <ch@murgatroid.com>
Cc: "'Frank Becker'" <fbecker@intrinsyc.com>,
linux-arm-kernel@lists.arm.linux.org.uk,
"'linux-mtd'" <linux-mtd@lists.infradead.org>,
akpm@digeo.com, linux-kernel@vger.kernel.org
Subject: Re: 2.5.55-rmk1: user space lossage
Date: Thu, 23 Jan 2003 09:48:23 +0000 [thread overview]
Message-ID: <15943.1043315303@passion.cambridge.redhat.com> (raw)
In-Reply-To: <000001c2c287$ffa8eef0$800b040f@bergamot>
< Snip long thread about init segfaulting immediately at boot on 2.5.55 >
ch@murgatroid.com said:
> I just dropped jffs2 from 2.5.52 into 2.5.55 and it works, too.
ch@murgatroid.com said:
> Aha! This is the problem:
> - .mmap = generic_file_mmap,
> + .mmap = generic_file_readonly_mmap,
> If you reverese this change, 2.5.55-rmk1 behaves.
Er, yes. generic_file_readonly_mmap() silently removed the VM_MAYWRITE bit
from vma->vm_flags when init made a _PRIVATE_ writable mapping, apparently
on the basis that we have no writepage().
Then we return success anyway.
Then init segfaults when it touches something in that mapping.
/me blames akpm. :)
--
dwmw2
WARNING: multiple messages have this Message-ID (diff)
From: David Woodhouse <dwmw2@infradead.org>
To: "Christopher Hoover" <ch@murgatroid.com>
Cc: "'Frank Becker'" <fbecker@intrinsyc.com>,
linux-arm-kernel@lists.arm.linux.org.uk,
"'linux-mtd'" <linux-mtd@lists.infradead.org>,
akpm@digeo.com, linux-kernel@vger.kernel.org
Subject: Re: 2.5.55-rmk1: user space lossage
Date: Thu, 23 Jan 2003 09:48:23 +0000 [thread overview]
Message-ID: <15943.1043315303@passion.cambridge.redhat.com> (raw)
In-Reply-To: <000001c2c287$ffa8eef0$800b040f@bergamot>
< Snip long thread about init segfaulting immediately at boot on 2.5.55 >
ch@murgatroid.com said:
> I just dropped jffs2 from 2.5.52 into 2.5.55 and it works, too.
ch@murgatroid.com said:
> Aha! This is the problem:
> - .mmap = generic_file_mmap,
> + .mmap = generic_file_readonly_mmap,
> If you reverese this change, 2.5.55-rmk1 behaves.
Er, yes. generic_file_readonly_mmap() silently removed the VM_MAYWRITE bit
from vma->vm_flags when init made a _PRIVATE_ writable mapping, apparently
on the basis that we have no writepage().
Then we return success anyway.
Then init segfaults when it touches something in that mapping.
/me blames akpm. :)
--
dwmw2
next prev parent reply other threads:[~2003-01-23 9:18 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <3E2F2354.7060508@intrinsyc.com>
2003-01-23 2:34 ` 2.5.55-rmk1: user space lossage Christopher Hoover
2003-01-23 9:48 ` David Woodhouse [this message]
2003-01-23 9:48 ` David Woodhouse
2003-01-23 9:56 ` Andrew Morton
2003-01-23 10:01 ` David Woodhouse
2003-01-23 10:01 ` David Woodhouse
2003-01-23 10:06 ` Andrew Morton
2003-01-23 17:57 ` Hugh Dickins
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