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Date: Sat, 27 Mar 2010 00:06:15 +0100
From: Johannes Weiner <hannes@...xchg.org>
To: Yinghai Lu <yinghai@...nel.org>
Cc: Ingo Molnar <mingo@...e.hu>, Thomas Gleixner <tglx@...utronix.de>,
"H. Peter Anvin" <hpa@...or.com>,
Andrew Morton <akpm@...ux-foundation.org>,
David Miller <davem@...emloft.net>,
Benjamin Herrenschmidt <benh@...nel.crashing.org>,
Linus Torvalds <torvalds@...ux-foundation.org>,
linux-kernel@...r.kernel.org, linux-arch@...r.kernel.org
Subject: Re: [PATCH 02/24] x86: Make sure free_init_pages() free pages in boundary
On Fri, Mar 26, 2010 at 03:21:32PM -0700, Yinghai Lu wrote:
> diff --git a/arch/x86/kernel/head32.c b/arch/x86/kernel/head32.c
> index adedeef..fe3d953 100644
> --- a/arch/x86/kernel/head32.c
> +++ b/arch/x86/kernel/head32.c
> @@ -47,6 +47,7 @@ void __init i386_start_kernel(void)
> u64 ramdisk_image = boot_params.hdr.ramdisk_image;
> u64 ramdisk_size = boot_params.hdr.ramdisk_size;
> u64 ramdisk_end = ramdisk_image + ramdisk_size;
> + ramdisk_end = PFN_UP(ramdisk_end) << PAGE_SHIFT;
Why not PAGE_ALIGN()?
> reserve_early(ramdisk_image, ramdisk_end, "RAMDISK");
> }
> #endif
> diff --git a/arch/x86/kernel/head64.c b/arch/x86/kernel/head64.c
> index b5a9896..fafba92 100644
> --- a/arch/x86/kernel/head64.c
> +++ b/arch/x86/kernel/head64.c
> @@ -106,6 +106,7 @@ void __init x86_64_start_reservations(char *real_mode_data)
> unsigned long ramdisk_image = boot_params.hdr.ramdisk_image;
> unsigned long ramdisk_size = boot_params.hdr.ramdisk_size;
> unsigned long ramdisk_end = ramdisk_image + ramdisk_size;
> + ramdisk_end = PFN_UP(ramdisk_end) << PAGE_SHIFT;
Dito
> reserve_early(ramdisk_image, ramdisk_end, "RAMDISK");
> }
> #endif
> diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c
> index 5d7ba1a..2a1b9d4 100644
> --- a/arch/x86/kernel/setup.c
> +++ b/arch/x86/kernel/setup.c
> @@ -317,57 +317,61 @@ static void __init relocate_initrd(void)
>
> u64 ramdisk_image = boot_params.hdr.ramdisk_image;
> u64 ramdisk_size = boot_params.hdr.ramdisk_size;
> + u64 ramdisk_end = ramdisk_image + ramdisk_size;
> u64 end_of_lowmem = max_low_pfn_mapped << PAGE_SHIFT;
> + u64 image, size_aligned;
> u64 ramdisk_here;
> unsigned long slop, clen, mapaddr;
> char *p, *q;
>
> + ramdisk_end = PFN_UP(ramdisk_end) << PAGE_SHIFT;
Dito
> + size_aligned = ramdisk_end - ramdisk_image;
> +
> /* We need to move the initrd down into lowmem */
> - ramdisk_here = find_e820_area(0, end_of_lowmem, ramdisk_size,
> + ramdisk_here = find_e820_area(0, end_of_lowmem, size_aligned,
> PAGE_SIZE);
>
> if (ramdisk_here == -1ULL)
> panic("Cannot find place for new RAMDISK of size %lld\n",
> - ramdisk_size);
> + size_aligned);
>
> /* Note: this includes all the lowmem currently occupied by
> the initrd, we rely on that fact to keep the data intact. */
> - reserve_early(ramdisk_here, ramdisk_here + ramdisk_size,
> + reserve_early(ramdisk_here, ramdisk_here + size_aligned,
> "NEW RAMDISK");
> initrd_start = ramdisk_here + PAGE_OFFSET;
> initrd_end = initrd_start + ramdisk_size;
> printk(KERN_INFO "Allocated new RAMDISK: %08llx - %08llx\n",
> - ramdisk_here, ramdisk_here + ramdisk_size);
> + ramdisk_here, ramdisk_here + size_aligned);
>
> q = (char *)initrd_start;
>
> /* Copy any lowmem portion of the initrd */
> - if (ramdisk_image < end_of_lowmem) {
> - clen = end_of_lowmem - ramdisk_image;
> - p = (char *)__va(ramdisk_image);
> + image = ramdisk_image;
> + if (image < end_of_lowmem) {
> + clen = end_of_lowmem - image;
> + p = (char *)__va(image);
> memcpy(q, p, clen);
> q += clen;
> - ramdisk_image += clen;
> - ramdisk_size -= clen;
> + image += clen;
> + size_aligned -= clen;
> }
>
> /* Copy the highmem portion of the initrd */
> - while (ramdisk_size) {
> - slop = ramdisk_image & ~PAGE_MASK;
> - clen = ramdisk_size;
> + while (size_aligned) {
> + slop = image & ~PAGE_MASK;
> + clen = size_aligned;
> if (clen > MAX_MAP_CHUNK-slop)
> clen = MAX_MAP_CHUNK-slop;
> - mapaddr = ramdisk_image & PAGE_MASK;
> + mapaddr = image & PAGE_MASK;
> p = early_memremap(mapaddr, clen+slop);
> memcpy(q, p+slop, clen);
> early_iounmap(p, clen+slop);
> q += clen;
> - ramdisk_image += clen;
> - ramdisk_size -= clen;
> + image += clen;
> + size_aligned -= clen;
Those appear to be a lot of spurious changes. We don't need to
copy the alignment padding as well, so it only matters that the
arguments to find_e820_area() and reserve_early() are aligned, no?
> }
> /* high pages is not converted by early_res_to_bootmem */
> - ramdisk_image = boot_params.hdr.ramdisk_image;
> - ramdisk_size = boot_params.hdr.ramdisk_size;
> printk(KERN_INFO "Move RAMDISK from %016llx - %016llx to"
> " %08llx - %08llx\n",
> ramdisk_image, ramdisk_image + ramdisk_size - 1,
> @@ -385,6 +389,8 @@ static void __init reserve_initrd(void)
> !ramdisk_image || !ramdisk_size)
> return; /* No initrd provided by bootloader */
>
> + ramdisk_end = PFN_UP(ramdisk_end) << PAGE_SHIFT;
Dito
> diff --git a/arch/x86/mm/init.c b/arch/x86/mm/init.c
> index e71c5cb..727d6b0 100644
> --- a/arch/x86/mm/init.c
> +++ b/arch/x86/mm/init.c
> @@ -332,6 +332,16 @@ int devmem_is_allowed(unsigned long pagenr)
> void free_init_pages(char *what, unsigned long begin, unsigned long end)
> {
> unsigned long addr = begin;
> + unsigned long addr_aligned, end_aligned;
> +
> + /* Make sure boundaries are page aligned */
> + addr_aligned = PFN_UP(addr) << PAGE_SHIFT;
> + end_aligned = PFN_DOWN(end) << PAGE_SHIFT;
> +
> + if (WARN(addr_aligned != addr || end_aligned != end, "free_init_pages: range [%#lx, %#lx] is not aligned\n", addr, end)) {
> + addr = addr_aligned;
> + end = end_aligned;
> + }
Maybe realign only for when it is not aligned? So to keep the fixup
out of line.
I suppose WARN_ON() is enough as it will print a stack trace which
should be enough clue of what went wrong.
> if (addr >= end)
> return;
> @@ -376,6 +386,18 @@ void free_initmem(void)
> #ifdef CONFIG_BLK_DEV_INITRD
> void free_initrd_mem(unsigned long start, unsigned long end)
> {
> - free_init_pages("initrd memory", start, end);
> + unsigned long end_aligned;
> +
> + /*
> + * end could be not aligned, and We can not align that,
> + * decompresser could be confused by aligned initrd_end
> + * We already reserve the end partial page before in
> + * - i386_start_kernel()
> + * - x86_64_start_kernel()
> + * - relocate_initrd()
> + * So here we can do PFN_UP() safely to get partial page to be freed
> + */
> + end_aligned = PFN_UP(end) << PAGE_SHIFT;
PAGE_ALIGN()
> + free_init_pages("initrd memory", start, end_aligned);
> }
> #endif
--
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