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Message-ID: <4BAD5D25.5060909@kernel.org>
Date: Fri, 26 Mar 2010 18:19:33 -0700
From: Yinghai Lu <yinghai@...nel.org>
To: Johannes Weiner <hannes@...xchg.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: [PATCH -v3] x86: Make sure free_init_pages() free pages in boundary
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@...hat.com>
Signed-off-by: Yinghai Lu <yinghai@...nel.org>
Acked-by: Johannes Weiner <hannes@...xchg.org>
Tested-by: Stanislaw Gruszka <sgruszka@...hat.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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