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[2001:44b8:111e:5c00:61b9:31c:bed1:3502]) by smtp.gmail.com with ESMTPSA id c9sm12165045pfn.65.2019.12.05.06.04.15 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 05 Dec 2019 06:04:16 -0800 (PST) From: Daniel Axtens To: kasan-dev@googlegroups.com, linux-mm@kvack.org, aryabinin@virtuozzo.com, glider@google.com, linux-kernel@vger.kernel.org, dvyukov@google.com Cc: daniel@iogearbox.net, cai@lca.pw, Daniel Axtens Subject: [PATCH 2/3] kasan: use apply_to_existing_pages for releasing vmalloc shadow Date: Fri, 6 Dec 2019 01:04:06 +1100 Message-Id: <20191205140407.1874-2-dja@axtens.net> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20191205140407.1874-1-dja@axtens.net> References: <20191205140407.1874-1-dja@axtens.net> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: kasan_release_vmalloc uses apply_to_page_range to release vmalloc shadow. Unfortunately, apply_to_page_range can allocate memory to fill in page table entries, which is not what we want. Also, kasan_release_vmalloc is called under free_vmap_area_lock, so if apply_to_page_range does allocate memory, we get a sleep in atomic bug: BUG: sleeping function called from invalid context at mm/page_alloc.c:46= 81 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 Switch to using the apply_to_existing_pages helper instead, which won't allocate memory. Fixes: 3c5c3cfb9ef4 ("kasan: support backing vmalloc space with real shad= ow memory") Reported-by: Dmitry Vyukov Cc: Andrey Ryabinin Signed-off-by: Daniel Axtens --- Andrew, if you want to take this, it replaces "kasan: Don't allocate page tables in kasan_release_vmalloc()" --- mm/kasan/common.c | 8 +++++--- 1 file changed, 5 insertions(+), 3 deletions(-) diff --git a/mm/kasan/common.c b/mm/kasan/common.c index e04e73603dfc..26fd0c13dd28 100644 --- a/mm/kasan/common.c +++ b/mm/kasan/common.c @@ -957,6 +957,7 @@ void kasan_release_vmalloc(unsigned long start, unsig= ned long end, { void *shadow_start, *shadow_end; unsigned long region_start, region_end; + unsigned long size; =20 region_start =3D ALIGN(start, PAGE_SIZE * KASAN_SHADOW_SCALE_SIZE); region_end =3D ALIGN_DOWN(end, PAGE_SIZE * KASAN_SHADOW_SCALE_SIZE); @@ -979,9 +980,10 @@ void kasan_release_vmalloc(unsigned long start, unsi= gned long end, shadow_end =3D kasan_mem_to_shadow((void *)region_end); =20 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); + size =3D shadow_end - shadow_start; + apply_to_existing_pages(&init_mm, (unsigned long)shadow_start, + size, kasan_depopulate_vmalloc_pte, + NULL); flush_tlb_kernel_range((unsigned long)shadow_start, (unsigned long)shadow_end); } --=20 2.20.1