Date: Mon, 16 Oct 2006 14:28:36 -0400 From: Vivek Goyal <vgoyal@redhat.com> Subject: [PATCH][RHEL5] BZ#210499: Avoid bss stomping by bootmem allocator initialization code This patch was discussed on LKML sometime back regarding one of the x86_64 boot problems. It solves the issue for BZ#210499. Posting it for inclusion in RHEL5. http://marc.theaimsgroup.com/?l=linux-netdev&m=116016517332266&w=2 I have forwarded the patch again to Andrew for inclusion in -mm. Thanks Vivek o Currently some code pieces assume that address returned by find_e820_area() are page aligned. But looks like find_e820_area() had no such intention and hence one might end up stomping over some of the data. One such case is bootmem allocator initialization code stomped over bss. o This patch modified find_e820_area() to return page aligned address. This might be little wasteful of memory but at the same time probably it is easier to handle page aligned memory. Signed-off-by: Vivek Goyal <vgoyal@in.ibm.com> --- arch/x86_64/kernel/e820.c | 14 +++++++------- 1 file changed, 7 insertions(+), 7 deletions(-) diff -puN arch/x86_64/kernel/e820.c~x86_64-return-page-aligned-phy-addr-from-find-e820-area arch/x86_64/kernel/e820.c --- linux-2.6.19-rc1-1M/arch/x86_64/kernel/e820.c~x86_64-return-page-aligned-phy-addr-from-find-e820-area 2006-10-06 15:28:13.000000000 -0400 +++ linux-2.6.19-rc1-1M-root/arch/x86_64/kernel/e820.c 2006-10-06 15:44:45.000000000 -0400 @@ -54,13 +54,13 @@ static inline int bad_addr(unsigned long /* various gunk below that needed for SMP startup */ if (addr < 0x8000) { - *addrp = 0x8000; + *addrp = PAGE_ALIGN(0x8000); return 1; } /* direct mapping tables of the kernel */ if (last >= table_start<<PAGE_SHIFT && addr < table_end<<PAGE_SHIFT) { - *addrp = table_end << PAGE_SHIFT; + *addrp = PAGE_ALIGN(table_end << PAGE_SHIFT); return 1; } @@ -65,7 +65,7 @@ static inline int bad_addr(unsigned long #ifdef CONFIG_BLK_DEV_INITRD if (LOADER_TYPE && INITRD_START && last >= INITRD_START && addr < INITRD_START+INITRD_SIZE) { - *addrp = INITRD_START + INITRD_SIZE; + *addrp = PAGE_ALIGN(INITRD_START + INITRD_SIZE); return 1; } #endif @@ -75,13 +75,13 @@ static inline int bad_addr(unsigned long *addrp = 1024*1024; return 1; } - if (last >= __pa_symbol(&_text) && last < __pa_symbol(&_end)) { - *addrp = __pa_symbol(&_end); + if (last >= __pa_symbol(&_text) && addr < __pa_symbol(&_end)) { + *addrp = PAGE_ALIGN(__pa_symbol(&_end)); return 1; } if (last >= ebda_addr && addr < ebda_addr + ebda_size) { - *addrp = ebda_addr + ebda_size; + *addrp = PAGE_ALIGN(ebda_addr + ebda_size); return 1; } @@ -152,7 +152,7 @@ unsigned long __init find_e820_area(unsi continue; while (bad_addr(&addr, size) && addr+size <= ei->addr+ei->size) ; - last = addr + size; + last = PAGE_ALIGN(addr) + size; if (last > ei->addr + ei->size) continue; if (last > end) _