path: root/arch/x86/kernel/head32.c
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authorYinghai Lu <yinghai@kernel.org>2010-03-28 19:42:55 -0700
committerIngo Molnar <mingo@elte.hu>2010-03-29 18:55:33 +0200
commitc967da6a0ba837f762042e931d4afcf72045547c (patch)
tree3576d2f97e20f3d8d647ea7381f5f99d96220fa2 /arch/x86/kernel/head32.c
parent596b711ed6b5235f8545680ef38ace00f9898c32 (diff)
x86: Make sure free_init_pages() frees pages on page boundary
When CONFIG_NO_BOOTMEM=y, it could use memory more effiently, or in a more compact fashion. Example: 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 be shared with other users. When free_init_pages are called for initrd or .init, the page could be freed and we could 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. So page align the boundaries. -v2: make the original initramdisk to be aligned, according to Johannes, otherwise we have the chance to lose one page. we still need to keep initrd_end not aligned, otherwise it could confuse decompressor. -v3: change to WARN_ON instead, suggested by Johannes. -v4: use PAGE_ALIGN, suggested by Johannes. We may fix that macro name later to PAGE_ALIGN_UP, and PAGE_ALIGN_DOWN Add comments about assuming ramdisk start is aligned in relocate_initrd(), change to re get ramdisk_image instead of save it to make diff smaller. Add warning for wrong range, suggested by Johannes. -v6: remove one WARN() We need to align beginning in free_init_pages() do not copy more than ramdisk_size, noticed by Johannes Reported-by: Stanislaw Gruszka <sgruszka@redhat.com> Tested-by: Stanislaw Gruszka <sgruszka@redhat.com> Signed-off-by: Yinghai Lu <yinghai@kernel.org> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Cc: David Miller <davem@davemloft.net> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> LKML-Reference: <1269830604-26214-3-git-send-email-yinghai@kernel.org> Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'arch/x86/kernel/head32.c')
1 files changed, 3 insertions, 1 deletions
diff --git a/arch/x86/kernel/head32.c b/arch/x86/kernel/head32.c
index adedeef1dedc..b2e246037392 100644
--- a/arch/x86/kernel/head32.c
+++ b/arch/x86/kernel/head32.c
@@ -7,6 +7,7 @@
#include <linux/init.h>
#include <linux/start_kernel.h>
+#include <linux/mm.h>
#include <asm/setup.h>
#include <asm/sections.h>
@@ -44,9 +45,10 @@ void __init i386_start_kernel(void)
/* Reserve INITRD */
if (boot_params.hdr.type_of_loader && boot_params.hdr.ramdisk_image) {
+ /* Assume only end is not page aligned */
u64 ramdisk_image = boot_params.hdr.ramdisk_image;
u64 ramdisk_size = boot_params.hdr.ramdisk_size;
- u64 ramdisk_end = ramdisk_image + ramdisk_size;
+ u64 ramdisk_end = PAGE_ALIGN(ramdisk_image + ramdisk_size);
reserve_early(ramdisk_image, ramdisk_end, "RAMDISK");

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