The patch titled Subject: kasan: Don't allocate page tables in kasan_release_vmalloc() has been added to the -mm tree. Its filename is kasan-dont-allocate-page-tables-in-kasan_release_vmalloc.patch This patch should soon appear at http://ozlabs.org/~akpm/mmots/broken-out/kasan-dont-allocate-page-tables-in-kasan_release_vmalloc.patch and later at http://ozlabs.org/~akpm/mmotm/broken-out/kasan-dont-allocate-page-tables-in-kasan_release_vmalloc.patch Before you just go and hit "reply", please: a) Consider who else should be cc'ed b) Prefer to cc a suitable mailing list as well c) Ideally: find the original patch on the mailing list and do a reply-to-all to that, adding suitable additional cc's *** Remember to use Documentation/process/submit-checklist.rst when testing your code *** The -mm tree is included into linux-next and is updated there every 3-4 working days ------------------------------------------------------ From: Andrey Ryabinin <aryabinin@xxxxxxxxxxxxx> Subject: kasan: Don't allocate page tables in kasan_release_vmalloc() The purpose of kasan_release_vmalloc() is to unmap and deallocate shadow memory. The usage of apply_to_page_range() isn't suitable in that scenario because it allocates pages to fill missing page tables entries. This also cause sleep in atomic bug: BUG: sleeping function called from invalid context at mm/page_alloc.c:4681 in_atomic(): 1, irqs_disabled(): 0, non_block: 0, pid: 15087, name: Call Trace: __dump_stack lib/dump_stack.c:77 [inline] dump_stack+0x199/0x216 lib/dump_stack.c:118 ___might_sleep.cold.97+0x1f5/0x238 kernel/sched/core.c:6800 __might_sleep+0x95/0x190 kernel/sched/core.c:6753 prepare_alloc_pages mm/page_alloc.c:4681 [inline] __alloc_pages_nodemask+0x3cd/0x890 mm/page_alloc.c:4730 alloc_pages_current+0x10c/0x210 mm/mempolicy.c:2211 alloc_pages include/linux/gfp.h:532 [inline] __get_free_pages+0xc/0x40 mm/page_alloc.c:4786 __pte_alloc_one_kernel include/asm-generic/pgalloc.h:21 [inline] pte_alloc_one_kernel include/asm-generic/pgalloc.h:33 [inline] __pte_alloc_kernel+0x1d/0x200 mm/memory.c:459 apply_to_pte_range mm/memory.c:2031 [inline] apply_to_pmd_range mm/memory.c:2068 [inline] apply_to_pud_range mm/memory.c:2088 [inline] apply_to_p4d_range mm/memory.c:2108 [inline] apply_to_page_range+0x77d/0xa00 mm/memory.c:2133 kasan_release_vmalloc+0xa7/0xc0 mm/kasan/common.c:970 __purge_vmap_area_lazy+0xcbb/0x1f30 mm/vmalloc.c:1313 try_purge_vmap_area_lazy mm/vmalloc.c:1332 [inline] free_vmap_area_noflush+0x2ca/0x390 mm/vmalloc.c:1368 free_unmap_vmap_area mm/vmalloc.c:1381 [inline] remove_vm_area+0x1cc/0x230 mm/vmalloc.c:2209 vm_remove_mappings mm/vmalloc.c:2236 [inline] __vunmap+0x223/0xa20 mm/vmalloc.c:2299 __vfree+0x3f/0xd0 mm/vmalloc.c:2356 __vmalloc_area_node mm/vmalloc.c:2507 [inline] __vmalloc_node_range+0x5d5/0x810 mm/vmalloc.c:2547 __vmalloc_node mm/vmalloc.c:2607 [inline] __vmalloc_node_flags mm/vmalloc.c:2621 [inline] vzalloc+0x6f/0x80 mm/vmalloc.c:2666 alloc_one_pg_vec_page net/packet/af_packet.c:4233 [inline] alloc_pg_vec net/packet/af_packet.c:4258 [inline] packet_set_ring+0xbc0/0x1b50 net/packet/af_packet.c:4342 packet_setsockopt+0xed7/0x2d90 net/packet/af_packet.c:3695 __sys_setsockopt+0x29b/0x4d0 net/socket.c:2117 __do_sys_setsockopt net/socket.c:2133 [inline] __se_sys_setsockopt net/socket.c:2130 [inline] __x64_sys_setsockopt+0xbe/0x150 net/socket.c:2130 do_syscall_64+0xfa/0x780 arch/x86/entry/common.c:294 entry_SYSCALL_64_after_hwframe+0x49/0xbe Add kasan_unmap_page_range() which skips empty page table entries instead of allocating them. Link: http://lkml.kernel.org/r/20191204204534.32202-2-aryabinin@xxxxxxxxxxxxx Fixes: 3c5c3cfb9ef4 ("kasan: support backing vmalloc space with real shadow memory") Signed-off-by: Andrey Ryabinin <aryabinin@xxxxxxxxxxxxx> Reported-by: Dmitry Vyukov <dvyukov@xxxxxxxxxx> Cc: Alexander Potapenko <glider@xxxxxxxxxx> Cc: Daniel Axtens <dja@xxxxxxxxxx> Cc: Qian Cai <cai@xxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- mm/kasan/common.c | 82 ++++++++++++++++++++++++++++++++++++-------- 1 file changed, 68 insertions(+), 14 deletions(-) --- a/mm/kasan/common.c~kasan-dont-allocate-page-tables-in-kasan_release_vmalloc +++ a/mm/kasan/common.c @@ -858,22 +858,77 @@ void kasan_unpoison_vmalloc(const void * kasan_unpoison_shadow(start, size); } -static int kasan_depopulate_vmalloc_pte(pte_t *ptep, unsigned long addr, - void *unused) +static void kasan_unmap_pte_range(pmd_t *pmd, unsigned long addr, + unsigned long end) { - unsigned long page; + pte_t *pte; - page = (unsigned long)__va(pte_pfn(*ptep) << PAGE_SHIFT); + pte = pte_offset_kernel(pmd, addr); + do { + pte_t ptent = ptep_get_and_clear(&init_mm, addr, pte); + + if (!pte_none(ptent)) + __free_page(pte_page(ptent)); + } while (pte++, addr += PAGE_SIZE, addr != end); +} - spin_lock(&init_mm.page_table_lock); +static void kasan_unmap_pmd_range(pud_t *pud, unsigned long addr, + unsigned long end) +{ + pmd_t *pmd; + unsigned long next; - if (likely(!pte_none(*ptep))) { - pte_clear(&init_mm, addr, ptep); - free_page(page); - } - spin_unlock(&init_mm.page_table_lock); + pmd = pmd_offset(pud, addr); + do { + next = pmd_addr_end(addr, end); + if (pmd_none_or_clear_bad(pmd)) + continue; + kasan_unmap_pte_range(pmd, addr, next); + } while (pmd++, addr = next, addr != end); +} + +static void kasan_unmap_pud_range(p4d_t *p4d, unsigned long addr, + unsigned long end) +{ + pud_t *pud; + unsigned long next; + + pud = pud_offset(p4d, addr); + do { + next = pud_addr_end(addr, end); + if (pud_none_or_clear_bad(pud)) + continue; + kasan_unmap_pmd_range(pud, addr, next); + } while (pud++, addr = next, addr != end); +} + +static void kasan_unmap_p4d_range(pgd_t *pgd, unsigned long addr, + unsigned long end) +{ + p4d_t *p4d; + unsigned long next; + + p4d = p4d_offset(pgd, addr); + do { + next = p4d_addr_end(addr, end); + if (p4d_none_or_clear_bad(p4d)) + continue; + kasan_unmap_pud_range(p4d, addr, next); + } while (p4d++, addr = next, addr != end); +} + +static void kasan_unmap_page_range(unsigned long addr, unsigned long end) +{ + pgd_t *pgd; + unsigned long next; - return 0; + pgd = pgd_offset_k(addr); + do { + next = pgd_addr_end(addr, end); + if (pgd_none_or_clear_bad(pgd)) + continue; + kasan_unmap_p4d_range(pgd, addr, next); + } while (pgd++, addr = next, addr != end); } /* @@ -979,9 +1034,8 @@ void kasan_release_vmalloc(unsigned long shadow_end = kasan_mem_to_shadow((void *)region_end); if (shadow_end > shadow_start) { - apply_to_page_range(&init_mm, (unsigned long)shadow_start, - (unsigned long)(shadow_end - shadow_start), - kasan_depopulate_vmalloc_pte, NULL); + kasan_unmap_page_range((unsigned long)shadow_start, + (unsigned long)shadow_end); flush_tlb_kernel_range((unsigned long)shadow_start, (unsigned long)shadow_end); } _ Patches currently in -mm which might be from aryabinin@xxxxxxxxxxxxx are kasan-fix-crashes-on-access-to-memory-mapped-by-vm_map_ram.patch kasan-dont-allocate-page-tables-in-kasan_release_vmalloc.patch