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authorYinghai Lu <yinghai@kernel.org>2010-03-28 22:42:55 -0400
committerIngo Molnar <mingo@elte.hu>2010-03-29 12:55:33 -0400
commitc967da6a0ba837f762042e931d4afcf72045547c (patch)
tree3576d2f97e20f3d8d647ea7381f5f99d96220fa2 /arch/x86/kernel/setup.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/setup.c')
-rw-r--r--arch/x86/kernel/setup.c10
1 files changed, 6 insertions, 4 deletions
diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c
index 5d7ba1a449bd..d76e18570c60 100644
--- a/arch/x86/kernel/setup.c
+++ b/arch/x86/kernel/setup.c
@@ -314,16 +314,17 @@ static void __init reserve_brk(void)
314#define MAX_MAP_CHUNK (NR_FIX_BTMAPS << PAGE_SHIFT) 314#define MAX_MAP_CHUNK (NR_FIX_BTMAPS << PAGE_SHIFT)
315static void __init relocate_initrd(void) 315static void __init relocate_initrd(void)
316{ 316{
317 317 /* Assume only end is not page aligned */
318 u64 ramdisk_image = boot_params.hdr.ramdisk_image; 318 u64 ramdisk_image = boot_params.hdr.ramdisk_image;
319 u64 ramdisk_size = boot_params.hdr.ramdisk_size; 319 u64 ramdisk_size = boot_params.hdr.ramdisk_size;
320 u64 area_size = PAGE_ALIGN(ramdisk_size);
320 u64 end_of_lowmem = max_low_pfn_mapped << PAGE_SHIFT; 321 u64 end_of_lowmem = max_low_pfn_mapped << PAGE_SHIFT;
321 u64 ramdisk_here; 322 u64 ramdisk_here;
322 unsigned long slop, clen, mapaddr; 323 unsigned long slop, clen, mapaddr;
323 char *p, *q; 324 char *p, *q;
324 325
325 /* We need to move the initrd down into lowmem */ 326 /* We need to move the initrd down into lowmem */
326 ramdisk_here = find_e820_area(0, end_of_lowmem, ramdisk_size, 327 ramdisk_here = find_e820_area(0, end_of_lowmem, area_size,
327 PAGE_SIZE); 328 PAGE_SIZE);
328 329
329 if (ramdisk_here == -1ULL) 330 if (ramdisk_here == -1ULL)
@@ -332,7 +333,7 @@ static void __init relocate_initrd(void)
332 333
333 /* Note: this includes all the lowmem currently occupied by 334 /* Note: this includes all the lowmem currently occupied by
334 the initrd, we rely on that fact to keep the data intact. */ 335 the initrd, we rely on that fact to keep the data intact. */
335 reserve_early(ramdisk_here, ramdisk_here + ramdisk_size, 336 reserve_early(ramdisk_here, ramdisk_here + area_size,
336 "NEW RAMDISK"); 337 "NEW RAMDISK");
337 initrd_start = ramdisk_here + PAGE_OFFSET; 338 initrd_start = ramdisk_here + PAGE_OFFSET;
338 initrd_end = initrd_start + ramdisk_size; 339 initrd_end = initrd_start + ramdisk_size;
@@ -376,9 +377,10 @@ static void __init relocate_initrd(void)
376 377
377static void __init reserve_initrd(void) 378static void __init reserve_initrd(void)
378{ 379{
380 /* Assume only end is not page aligned */
379 u64 ramdisk_image = boot_params.hdr.ramdisk_image; 381 u64 ramdisk_image = boot_params.hdr.ramdisk_image;
380 u64 ramdisk_size = boot_params.hdr.ramdisk_size; 382 u64 ramdisk_size = boot_params.hdr.ramdisk_size;
381 u64 ramdisk_end = ramdisk_image + ramdisk_size; 383 u64 ramdisk_end = PAGE_ALIGN(ramdisk_image + ramdisk_size);
382 u64 end_of_lowmem = max_low_pfn_mapped << PAGE_SHIFT; 384 u64 end_of_lowmem = max_low_pfn_mapped << PAGE_SHIFT;
383 385
384 if (!boot_params.hdr.type_of_loader || 386 if (!boot_params.hdr.type_of_loader ||