From: Andrew Morton <akpm@osdl.org>
To: Chris Wright <chrisw@osdl.org>
Cc: clameter@sgi.com, linux-kernel@vger.kernel.org
Subject: Re: panic on bootup due to __GFP_ZERO patch
Date: Sun, 9 Jan 2005 01:45:19 -0800 [thread overview]
Message-ID: <20050109014519.412688f6.akpm@osdl.org> (raw)
In-Reply-To: <20050108010629.M469@build.pdx.osdl.net>
Chris Wright <chrisw@osdl.org> wrote:
>
> I'm getting a panic during pidmap_init with a backtrace that looks
> something like:
>
> buffered_rmqueue
> __alloc_pages
> get_zeroed_page
> pidmap_init
> start_kernel
>
> Reverting the __GFP_ZERO patch fixes the issue, haven't drilled down
> any deeper yet to see what in the patch is causing the problem. This is
> x86 w/out HIGHMEM (and no NUMA).
>
Well it's doing clear_highpage() before __alloc_pages() has called
kernel_map_pages(), so CONFIG_DEBUG_PAGEALLOC is quite kaput.
So the current __GFP_ZERO buglist is:
1: Breaks CONFIG_DEBUG_PAGEALLOC
2: Breaks the cache aliasing protection for anonymous pages
3: prep_zero_page() uses KM_USER0 so __GFP_ZERO from IRQ context will
cause rare memory corruption.
next prev parent reply other threads:[~2005-01-09 9:45 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2005-01-08 9:06 Chris Wright
2005-01-08 20:00 ` Dave Jones
2005-01-09 9:45 ` Andrew Morton [this message]
2005-01-09 15:56 ` [PATCH] Fixes for prep_zero_page Zwane Mwaikambo
2005-01-09 20:52 ` Andrew Morton
2005-01-09 21:32 ` Zwane Mwaikambo
2005-01-09 22:48 ` Chris Wright
2005-01-10 4:18 ` Zwane Mwaikambo
2005-01-13 5:05 ` Zwane Mwaikambo
2005-01-13 18:24 ` Chris Wright
2005-01-14 0:50 ` Zwane Mwaikambo
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