From: Ingo Molnar <mingo@elte.hu>
To: Dave Young <hidave.darkstar@gmail.com>
Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org, hpa@zytor.com,
the arch/x86 maintainers <x86@kernel.org>
Subject: Re: [PATCH] kernel parameter vmalloc size fix
Date: Mon, 16 Jun 2008 10:01:31 +0200 [thread overview]
Message-ID: <20080616080131.GC25632@elte.hu> (raw)
In-Reply-To: <20080616042528.GA3003@darkstar.te-china.tietoenator.com>
* Dave Young <hidave.darkstar@gmail.com> wrote:
> booting kernel with vmalloc=[any size<=16m] will oops.
>
> It's due to the vm area hole.
>
> In include/asm-x86/pgtable_32.h:
> #define VMALLOC_OFFSET (8 * 1024 * 1024)
> #define VMALLOC_START (((unsigned long)high_memory + 2 * VMALLOC_OFFSET - 1) \
> & ~(VMALLOC_OFFSET - 1))
>
> BUG_ON in arch/x86/mm/init_32.c will be triggered:
> BUG_ON((unsigned long)high_memory > VMALLOC_START);
>
> Fixed by return -EINVAL for invalid parameter
hm. Why dont we instead add the size of the hole to the
__VMALLOC_RESERVE value instead? There's nothing inherently bad about
using vmalloc=16m. The VM area hole is really a kernel-internal
abstraction that should not be visible in the usage of the parameter.
Ingo
WARNING: multiple messages have this Message-ID (diff)
From: Ingo Molnar <mingo@elte.hu>
To: Dave Young <hidave.darkstar@gmail.com>
Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org, hpa@zytor.com,
the arch/x86 maintainers <x86@kernel.org>
Subject: Re: [PATCH] kernel parameter vmalloc size fix
Date: Mon, 16 Jun 2008 10:01:31 +0200 [thread overview]
Message-ID: <20080616080131.GC25632@elte.hu> (raw)
In-Reply-To: <20080616042528.GA3003@darkstar.te-china.tietoenator.com>
* Dave Young <hidave.darkstar@gmail.com> wrote:
> booting kernel with vmalloc=[any size<=16m] will oops.
>
> It's due to the vm area hole.
>
> In include/asm-x86/pgtable_32.h:
> #define VMALLOC_OFFSET (8 * 1024 * 1024)
> #define VMALLOC_START (((unsigned long)high_memory + 2 * VMALLOC_OFFSET - 1) \
> & ~(VMALLOC_OFFSET - 1))
>
> BUG_ON in arch/x86/mm/init_32.c will be triggered:
> BUG_ON((unsigned long)high_memory > VMALLOC_START);
>
> Fixed by return -EINVAL for invalid parameter
hm. Why dont we instead add the size of the hole to the
__VMALLOC_RESERVE value instead? There's nothing inherently bad about
using vmalloc=16m. The VM area hole is really a kernel-internal
abstraction that should not be visible in the usage of the parameter.
Ingo
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next prev parent reply other threads:[~2008-06-16 8:01 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-06-16 4:25 [PATCH] kernel parameter vmalloc size fix Dave Young
2008-06-16 4:25 ` Dave Young
2008-06-16 8:01 ` Ingo Molnar [this message]
2008-06-16 8:01 ` Ingo Molnar
2008-06-16 8:08 ` Dave Young
2008-06-16 8:08 ` Dave Young
2008-06-16 8:52 ` Dave Young
2008-06-16 8:52 ` Dave Young
2008-06-16 15:44 ` H. Peter Anvin
2008-06-16 15:44 ` H. Peter Anvin
2008-06-24 5:49 ` Dave Young
2008-06-26 12:14 ` Ingo Molnar
2008-06-26 12:14 ` Ingo Molnar
2008-06-27 1:55 ` Dave Young
2008-06-27 1:55 ` Dave Young
2008-07-11 7:05 ` Dave Young
2008-07-11 7:05 ` Dave Young
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