Messages in this thread Patch in this message | | | Date | Fri, 26 Mar 2010 18:19:33 -0700 | From | Yinghai Lu <> | Subject | [PATCH -v3] x86: Make sure free_init_pages() free pages in boundary |
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When CONFIG_NO_BOOTMEM, it could use memory more effient, 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.
-v2: make the original initramdisk to be aligned, according to Johannes. otherwise we have chance to lose one page. we still need to keep initrd_end not aligned, otherwise it could confuse decompresser. -v3: change to WARN_ON instead according to Johannes.
Reported-by: Stanislaw Gruszka <sgruszka@redhat.com> Signed-off-by: Yinghai Lu <yinghai@kernel.org> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Tested-by: Stanislaw Gruszka <sgruszka@redhat.com>
--- arch/x86/kernel/head32.c | 1 + arch/x86/kernel/head64.c | 1 + arch/x86/kernel/setup.c | 40 +++++++++++++++++++++++----------------- arch/x86/mm/init.c | 24 +++++++++++++++++++++++- 4 files changed, 48 insertions(+), 18 deletions(-)
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 @@ -332,6 +332,16 @@ int devmem_is_allowed(unsigned long page 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_ON(addr_aligned != addr || end_aligned != end)) { + addr = addr_aligned; + end = end_aligned; + } 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; + free_init_pages("initrd memory", start, end_aligned); } #endif Index: linux-2.6/arch/x86/kernel/head32.c =================================================================== --- linux-2.6.orig/arch/x86/kernel/head32.c +++ linux-2.6/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; reserve_early(ramdisk_image, ramdisk_end, "RAMDISK"); } #endif Index: linux-2.6/arch/x86/kernel/head64.c =================================================================== --- linux-2.6.orig/arch/x86/kernel/head64.c +++ linux-2.6/arch/x86/kernel/head64.c @@ -106,6 +106,7 @@ void __init x86_64_start_reservations(ch 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; reserve_early(ramdisk_image, ramdisk_end, "RAMDISK"); } #endif Index: linux-2.6/arch/x86/kernel/setup.c =================================================================== --- linux-2.6.orig/arch/x86/kernel/setup.c +++ linux-2.6/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; + 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; } /* 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; + initrd_start = 0; if (ramdisk_size >= (end_of_lowmem>>1)) {
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