| Message ID | 20190227171556.75444-1-cai@lca.pw (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | mm/page_ext: fix an imbalance with kmemleak | expand |
On Wed, Feb 27, 2019 at 12:15:56PM -0500, Qian Cai wrote: > After offlined a memory block, kmemleak scan will trigger a crash, as it > encounters a page ext address that has already been freed during memory > offlining. At the beginning in alloc_page_ext(), it calls > kmemleak_alloc(), but it does not call kmemleak_free() in > __free_page_ext(). [...] > diff --git a/mm/page_ext.c b/mm/page_ext.c > index 8c78b8d45117..b68f2a58ea3b 100644 > --- a/mm/page_ext.c > +++ b/mm/page_ext.c > @@ -288,6 +288,7 @@ static void __free_page_ext(unsigned long pfn) > base = get_entry(ms->page_ext, pfn); > free_page_ext(base); > ms->page_ext = NULL; > + kmemleak_free(base); > } The kmemleak_free() call should be placed before free_page_ext() to avoid a small window where the address has been freed but kmemleak not informed.
diff --git a/mm/page_ext.c b/mm/page_ext.c index 8c78b8d45117..b68f2a58ea3b 100644 --- a/mm/page_ext.c +++ b/mm/page_ext.c @@ -288,6 +288,7 @@ static void __free_page_ext(unsigned long pfn) base = get_entry(ms->page_ext, pfn); free_page_ext(base); ms->page_ext = NULL; + kmemleak_free(base); } static int __meminit online_page_ext(unsigned long start_pfn,
After offlined a memory block, kmemleak scan will trigger a crash, as it encounters a page ext address that has already been freed during memory offlining. At the beginning in alloc_page_ext(), it calls kmemleak_alloc(), but it does not call kmemleak_free() in __free_page_ext(). BUG: unable to handle kernel paging request at ffff888453d00000 PGD 128a01067 P4D 128a01067 PUD 128a04067 PMD 47e09e067 PTE 800ffffbac2ff060 Oops: 0000 [#1] SMP DEBUG_PAGEALLOC KASAN PTI CPU: 1 PID: 1594 Comm: bash Not tainted 5.0.0-rc8+ #15 Hardware name: HP ProLiant DL180 Gen9/ProLiant DL180 Gen9, BIOS U20 10/25/2017 RIP: 0010:scan_block+0xb5/0x290 Code: 85 6e 01 00 00 48 b8 00 00 30 f5 81 88 ff ff 48 39 c3 0f 84 5b 01 00 00 48 89 d8 48 c1 e8 03 42 80 3c 20 00 0f 85 87 01 00 00 <4c> 8b 3b e8 f3 0c fa ff 4c 39 3d 0c 6b 4c 01 0f 87 08 01 00 00 4c RSP: 0018:ffff8881ec57f8e0 EFLAGS: 00010082 RAX: 0000000000000000 RBX: ffff888453d00000 RCX: ffffffffa61e5a54 RDX: 0000000000000000 RSI: 0000000000000008 RDI: ffff888453d00000 RBP: ffff8881ec57f920 R08: fffffbfff4ed588d R09: fffffbfff4ed588c R10: fffffbfff4ed588c R11: ffffffffa76ac463 R12: dffffc0000000000 R13: ffff888453d00ff9 R14: ffff8881f80cef48 R15: ffff8881f80cef48 FS: 00007f6c0e3f8740(0000) GS:ffff8881f7680000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: ffff888453d00000 CR3: 00000001c4244003 CR4: 00000000001606a0 Call Trace: scan_gray_list+0x269/0x430 kmemleak_scan+0x5a8/0x10f0 kmemleak_write+0x541/0x6ca full_proxy_write+0xf8/0x190 __vfs_write+0xeb/0x980 vfs_write+0x15a/0x4f0 ksys_write+0xd2/0x1b0 __x64_sys_write+0x73/0xb0 do_syscall_64+0xeb/0xaaa entry_SYSCALL_64_after_hwframe+0x44/0xa9 RIP: 0033:0x7f6c0dad73b8 Code: 89 02 48 c7 c0 ff ff ff ff eb b3 0f 1f 80 00 00 00 00 f3 0f 1e fa 48 8d 05 65 63 2d 00 8b 00 85 c0 75 17 b8 01 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 58 c3 0f 1f 80 00 00 00 00 41 54 49 89 d4 55 RSP: 002b:00007ffd5b863cb8 EFLAGS: 00000246 ORIG_RAX: 0000000000000001 RAX: ffffffffffffffda RBX: 0000000000000005 RCX: 00007f6c0dad73b8 RDX: 0000000000000005 RSI: 000055a9216e1710 RDI: 0000000000000001 RBP: 000055a9216e1710 R08: 000000000000000a R09: 00007ffd5b863840 R10: 000000000000000a R11: 0000000000000246 R12: 00007f6c0dda9780 R13: 0000000000000005 R14: 00007f6c0dda4740 R15: 0000000000000005 Modules linked in: nls_iso8859_1 nls_cp437 vfat fat kvm_intel kvm irqbypass efivars ip_tables x_tables xfs sd_mod ahci libahci igb i2c_algo_bit libata i2c_core dm_mirror dm_region_hash dm_log dm_mod efivarfs CR2: ffff888453d00000 ---[ end trace ccf646c7456717c5 ]--- RIP: 0010:scan_block+0xb5/0x290 Code: 85 6e 01 00 00 48 b8 00 00 30 f5 81 88 ff ff 48 39 c3 0f 84 5b 01 00 00 48 89 d8 48 c1 e8 03 42 80 3c 20 00 0f 85 87 01 00 00 <4c> 8b 3b e8 f3 0c fa ff 4c 39 3d 0c 6b 4c 01 0f 87 08 01 00 00 4c RSP: 0018:ffff8881ec57f8e0 EFLAGS: 00010082 RAX: 0000000000000000 RBX: ffff888453d00000 RCX: ffffffffa61e5a54 RDX: 0000000000000000 RSI: 0000000000000008 RDI: ffff888453d00000 RBP: ffff8881ec57f920 R08: fffffbfff4ed588d R09: fffffbfff4ed588c R10: fffffbfff4ed588c R11: ffffffffa76ac463 R12: dffffc0000000000 R13: ffff888453d00ff9 R14: ffff8881f80cef48 R15: ffff8881f80cef48 FS: 00007f6c0e3f8740(0000) GS:ffff8881f7680000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: ffff888453d00000 CR3: 00000001c4244003 CR4: 00000000001606a0 Kernel panic - not syncing: Fatal exception Shutting down cpus with NMI Kernel Offset: 0x24c00000 from 0xffffffff81000000 (relocation range: 0xffffffff80000000-0xffffffffbfffffff) ---[ end Kernel panic - not syncing: Fatal exception ]--- Signed-off-by: Qian Cai <cai@lca.pw> --- mm/page_ext.c | 1 + 1 file changed, 1 insertion(+)