Messages in this thread Patch in this message | | | Date | Tue, 25 Oct 2022 18:39:07 +0300 | Subject | Re: [tip:x86/mm] [x86/mm] 1248fb6a82: Kernel_panic-not_syncing:kasan_populate_pmd:Failed_to_allocate_page | From | Andrey Ryabinin <> |
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On 10/25/22 13:33, Peter Zijlstra wrote: > On Tue, Oct 25, 2022 at 12:54:40PM +0800, kernel test robot wrote: >> Hi Peter, >> >> We noticed that below commit changed the value of >> CPU_ENTRY_AREA_MAP_SIZE. Seems KASAN uses this value to allocate memory, >> and failed during initialization after this change, so we send this >> mail and Cc KASAN folks. Please kindly check below report for more >> details. Thanks. >> >> >> Greeting, >> >> FYI, we noticed Kernel_panic-not_syncing:kasan_populate_pmd:Failed_to_allocate_page due to commit (built with gcc-11): >> >> commit: 1248fb6a8201ddac1c86a202f05a0a1765efbfce ("x86/mm: Randomize per-cpu entry area") >> https://git.kernel.org/cgit/linux/kernel/git/tip/tip.git x86/mm >> >> in testcase: boot >> >> on test machine: qemu-system-x86_64 -enable-kvm -cpu SandyBridge -smp 2 -m 16G >> >> caused below changes (please refer to attached dmesg/kmsg for entire log/backtrace): >> >> >> [ 7.114808][ T0] Kernel panic - not syncing: kasan_populate_pmd+0x142/0x1d2: Failed to allocate page, nid=0 from=1000000 >> [ 7.119742][ T0] CPU: 0 PID: 0 Comm: swapper Not tainted 6.1.0-rc1-00001-g1248fb6a8201 #1 >> [ 7.122122][ T0] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.16.0-debian-1.16.0-4 04/01/2014 >> [ 7.124976][ T0] Call Trace: >> [ 7.125849][ T0] <TASK> >> [ 7.126642][ T0] ? dump_stack_lvl+0x45/0x5d >> [ 7.127908][ T0] ? panic+0x21e/0x46a >> [ 7.129009][ T0] ? panic_print_sys_info+0x77/0x77 >> [ 7.130618][ T0] ? memblock_alloc_try_nid_raw+0x106/0x106 >> [ 7.132224][ T0] ? memblock_alloc_try_nid+0xd9/0x118 >> [ 7.133717][ T0] ? memblock_alloc_try_nid_raw+0x106/0x106 >> [ 7.135252][ T0] ? kasan_populate_pmd+0x142/0x1d2 >> [ 7.136655][ T0] ? early_alloc+0x95/0x9d >> [ 7.137738][ T0] ? kasan_populate_pmd+0x142/0x1d2 >> [ 7.138936][ T0] ? kasan_populate_pud+0x182/0x19f >> [ 7.140335][ T0] ? kasan_populate_shadow+0x1e0/0x233 >> [ 7.141759][ T0] ? kasan_init+0x3be/0x57f >> [ 7.142942][ T0] ? setup_arch+0x101d/0x11f0 >> [ 7.144229][ T0] ? start_kernel+0x6f/0x3d0 >> [ 7.145449][ T0] ? secondary_startup_64_no_verify+0xe0/0xeb >> [ 7.147051][ T0] </TASK> >> [ 7.147868][ T0] ---[ end Kernel panic - not syncing: kasan_populate_pmd+0x142/0x1d2: Failed to allocate page, nid=0 from=1000000 ]--- > > Ufff, no idea about what KASAN wants here; Andrey, you have clue? > > Are you trying to allocate backing space for .5T of vspace and failing > that because the kvm thing doesn't have enough memory? >
KASAN tries to allocate shadow memory for the whole cpu entry area. The size is CPU_ENTRY_AREA_MAP_SIZE/8 and this is obviously fails after your patch. The fix this might be something like this:
--- arch/x86/include/asm/kasan.h | 2 ++ arch/x86/mm/cpu_entry_area.c | 3 +++ arch/x86/mm/kasan_init_64.c | 16 +++++++++++++--- 3 files changed, 18 insertions(+), 3 deletions(-)
diff --git a/arch/x86/include/asm/kasan.h b/arch/x86/include/asm/kasan.h index 13e70da38bed..77dd8b57f1e2 100644 --- a/arch/x86/include/asm/kasan.h +++ b/arch/x86/include/asm/kasan.h @@ -28,9 +28,11 @@ #ifdef CONFIG_KASAN void __init kasan_early_init(void); void __init kasan_init(void); +void __init kasan_populate_shadow_for_vaddr(void *va, size_t size); #else static inline void kasan_early_init(void) { } static inline void kasan_init(void) { } +static inline void kasan_populate_shadow_for_vaddr(void *va, size_t size) { } #endif #endif diff --git a/arch/x86/mm/cpu_entry_area.c b/arch/x86/mm/cpu_entry_area.c index ad1f750517a1..602daa550543 100644 --- a/arch/x86/mm/cpu_entry_area.c +++ b/arch/x86/mm/cpu_entry_area.c @@ -9,6 +9,7 @@ #include <asm/cpu_entry_area.h> #include <asm/fixmap.h> #include <asm/desc.h> +#include <asm/kasan.h> static DEFINE_PER_CPU_PAGE_ALIGNED(struct entry_stack_page, entry_stack_storage); @@ -91,6 +92,8 @@ void cea_set_pte(void *cea_vaddr, phys_addr_t pa, pgprot_t flags) static void __init cea_map_percpu_pages(void *cea_vaddr, void *ptr, int pages, pgprot_t prot) { + kasan_populate_shadow_for_vaddr(cea_vaddr, pages*PAGE_SIZE); + for ( ; pages; pages--, cea_vaddr+= PAGE_SIZE, ptr += PAGE_SIZE) cea_set_pte(cea_vaddr, per_cpu_ptr_to_phys(ptr), prot); } diff --git a/arch/x86/mm/kasan_init_64.c b/arch/x86/mm/kasan_init_64.c index e7b9b464a82f..dbee52f14700 100644 --- a/arch/x86/mm/kasan_init_64.c +++ b/arch/x86/mm/kasan_init_64.c @@ -316,6 +316,19 @@ void __init kasan_early_init(void) kasan_map_early_shadow(init_top_pgt); } +void __init kasan_populate_shadow_for_vaddr(void *va, size_t size) +{ + unsigned long shadow_start, shadow_end; + + shadow_start = (unsigned long)kasan_mem_to_shadow(va); + shadow_start = round_down(shadow_start, PAGE_SIZE); + shadow_end = (unsigned long)kasan_mem_to_shadow(va + size); + shadow_end = round_up(shadow_end, PAGE_SIZE); + + kasan_populate_shadow(shadow_start, shadow_end, + early_pfn_to_nid(__pa(va))); +} + void __init kasan_init(void) { int i; @@ -393,9 +406,6 @@ void __init kasan_init(void) kasan_mem_to_shadow((void *)VMALLOC_END + 1), shadow_cpu_entry_begin); - kasan_populate_shadow((unsigned long)shadow_cpu_entry_begin, - (unsigned long)shadow_cpu_entry_end, 0); - kasan_populate_early_shadow(shadow_cpu_entry_end, kasan_mem_to_shadow((void *)__START_KERNEL_map)); -- 2.37.4
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