Re: Can not boot with CONFIG_NO_BOOTMEM=y on i686

[Johannes Weiner <hannes@cmpxchg.org>]

On Fri, Mar 26, 2010 at 01:10:43AM -0700, Yinghai Lu wrote:
> On 03/24/2010 02:04 AM, Stanislaw Gruszka wrote:
> > On Tue, Mar 23, 2010 at 09:06:00PM -0700, Yinghai Lu wrote:
> >> On 03/23/2010 04:35 AM, Stanislaw Gruszka wrote:
> >>> On Sat, Mar 20, 2010 at 11:26:06AM -0700, Yinghai Lu wrote:
> >>>>> After update to 2.6.34-rc1, I was experimented by strange oopses during
> >>>>> boot, what looked like memory corruption. Bisection shows that first bad
> >>>>> commit is 59be5a8e8ce765cf739ec7f07176219972de7481 ("x86: Make 32bit
> >>>>> support NO_BOOTMEM"). When I disable CONFIG_NO_BOOTMEM I'm able to start
> >>>>> system. Not sure what info is need to track down this issue, so please
> >>>>> let me know.
> >>>>
> >>>> can you check patch
> >>>>
> >>>> https://patchwork.kernel.org/patch/87081/
> >>>
> >>> Patch helps somehow. Instead of many random oopses, now I have one and
> >>> the same oops, here is photo:
> >>> http://people.redhat.com/sgruszka/20100322_001.jpg
> >>
> >> how does e820 look like?
> > 
> > dmesg below, I hope everything you asked for is here:
> > 
> > Linux version 2.6.34-rc1 (stasiu@yellow) (gcc version 4.4.2 20091222 (Red Hat 4.4.2-20) (GCC) ) #26 SMP Tue Mar 23 11:31:22 CET 2010
> > BIOS-provided physical RAM map:
> >  BIOS-e820: 0000000000000000 - 0000000000096400 (usable)
> >  BIOS-e820: 0000000000096400 - 00000000000a0000 (reserved)
> >  BIOS-e820: 00000000000e8000 - 0000000000100000 (reserved)
> >  BIOS-e820: 0000000000100000 - 00000000cffc2840 (usable)
> >  BIOS-e820: 00000000cffc2840 - 00000000d0000000 (reserved)
> >  BIOS-e820: 00000000e0000000 - 00000000f0000000 (reserved)
> >  BIOS-e820: 00000000fec00000 - 0000000100000000 (reserved)
> >  BIOS-e820: 0000000100000000 - 0000000130000000 (usable)
> ...
> > initial memory mapped : 0 - 01000000
> > found SMP MP-table at [c00fe700] fe700
> > init_memory_mapping: 0000000000000000-00000000373fe000
> >  0000000000 - 0000400000 page 4k
> >  0000400000 - 0037000000 page 2M
> >  0037000000 - 00373fe000 page 4k
> > kernel direct mapping tables up to 373fe000 @ 7000-d000
> > RAMDISK: 373b8000 - 37fef224
> > Allocated new RAMDISK: 00b2f000 - 01766224
> > Move RAMDISK from 00000000373b8000 - 0000000037fef223 to 00b2f000 - 01766223
> > Reserving 256MB of memory at 32MB for crashkernel (System RAM: 3327MB)
> 
> Please check if this one helps
> 
> Thanks
> 
> Yinghai
> 
> ---
> [PATCH] x86: Make sure free_init_pages() free pages in boundary
> 
> When CONFIG_NO_BOOTMEM, it could use memory more efficient, or more compact.
> 
> Example is:
> Allocated new RAMDISK: 00ec2000 - 0248ce57
> Move RAMDISK from 000000002ea04000 - 000000002ffcee56 to 00ec2000 - 0248ce56
> 
> The new RAMDISK's end is not page aligned.
> Last page could use shared with other user.
> 
> When free_init_pages are called for initrd or .init, the page could be freed
> could have chance to corrupt other data.
> 
> code segment in free_init_pages()
> |        for (; addr < end; addr += PAGE_SIZE) {
> |                ClearPageReserved(virt_to_page(addr));
> |                init_page_count(virt_to_page(addr));
> |                memset((void *)(addr & ~(PAGE_SIZE-1)),
> |                        POISON_FREE_INITMEM, PAGE_SIZE);
> |                free_page(addr);
> |                totalram_pages++;
> |        }
> last half page could be used as one whole free page.
> 
> Try to make the boundaries to be page aligned.

Makes sense to align the addresses, but not in free_init_pages().  The
name says 'pages' and all callers but free_initrd_mem() get it right.

Could you maybe move the fixup to that function instead?

> Signed-off-by: Yinghai Lu <yinghai@kernel.org>

Acked-by: Johannes Weiner <hannes@cmpxchg.org>

> ---
>  arch/x86/mm/init.c |    4 ++++
>  1 file changed, 4 insertions(+)
> 
> Index: linux-2.6/arch/x86/mm/init.c
> ===================================================================
> --- linux-2.6.orig/arch/x86/mm/init.c
> +++ linux-2.6/arch/x86/mm/init.c
> @@ -334,6 +334,10 @@ void free_init_pages(char *what, unsigne
>  {
>  	unsigned long addr = begin;
>  
> +	/* Make sure boundaries are page aligned */
> +	addr = PFN_UP(addr) << PAGE_SHIFT;
> +	end = PFN_DOWN(end) << PAGE_SHIFT;
> +
>  	if (addr >= end)
>  		return;
>  
> --
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