On an arm64 ThunderX2 server, the first kmemleak scan would crash [1]
with CONFIG_DEBUG_VM_PGFLAGS=y due to page_to_nid() found a pfn that is
not directly mapped (MEMBLOCK_NOMAP). Hence, the page->flags is
uninitialized.
This is due to the commit
9f1eb38e0e11 ("mm, kmemleak: little
optimization while scanning") starts to use pfn_to_online_page() instead
of pfn_valid(). However, in the CONFIG_MEMORY_HOTPLUG=y case,
pfn_to_online_page() does not call memblock_is_map_memory() while
pfn_valid() does.
Historically, the commit
68709f45385a ("arm64: only consider memblocks
with NOMAP cleared for linear mapping") causes pages marked as nomap
being no long reassigned to the new zone in memmap_init_zone() by
calling __init_single_page().
Since the commit
2d070eab2e82 ("mm: consider zone which is not fully
populated to have holes") introduced pfn_to_online_page() and was
designed to return a valid pfn only, but it is clearly broken on arm64.
Therefore, let pfn_to_online_page() call pfn_valid_within(), so it can
handle nomap thanks to the commit
f52bb98f5ade ("arm64: mm: always
enable CONFIG_HOLES_IN_ZONE"), while it will be optimized away on
architectures where have no HOLES_IN_ZONE.
[1]
Unable to handle kernel NULL pointer dereference at virtual address
0000000000000006
Mem abort info:
ESR = 0x96000005
Exception class = DABT (current EL), IL = 32 bits
SET = 0, FnV = 0
EA = 0, S1PTW = 0
Data abort info:
ISV = 0, ISS = 0x00000005
CM = 0, WnR = 0
Internal error: Oops:
96000005 [#1] SMP
CPU: 60 PID: 1408 Comm: kmemleak Not tainted 5.0.0-rc2+ #8
pstate:
60400009 (nZCv daif +PAN -UAO)
pc : page_mapping+0x24/0x144
lr : __dump_page+0x34/0x3dc
sp :
ffff00003a5cfd10
x29:
ffff00003a5cfd10 x28:
000000000000802f
x27:
0000000000000000 x26:
0000000000277d00
x25:
ffff000010791f56 x24:
ffff7fe000000000
x23:
ffff000010772f8b x22:
ffff00001125f670
x21:
ffff000011311000 x20:
ffff000010772f8b
x19:
fffffffffffffffe x18:
0000000000000000
x17:
0000000000000000 x16:
0000000000000000
x15:
0000000000000000 x14:
ffff802698b19600
x13:
ffff802698b1a200 x12:
ffff802698b16f00
x11:
ffff802698b1a400 x10:
0000000000001400
x9 :
0000000000000001 x8 :
ffff00001121a000
x7 :
0000000000000000 x6 :
ffff0000102c53b8
x5 :
0000000000000000 x4 :
0000000000000003
x3 :
0000000000000100 x2 :
0000000000000000
x1 :
ffff000010772f8b x0 :
ffffffffffffffff
Process kmemleak (pid: 1408, stack limit = 0x(____ptrval____))
Call trace:
page_mapping+0x24/0x144
__dump_page+0x34/0x3dc
dump_page+0x28/0x4c
kmemleak_scan+0x4ac/0x680
kmemleak_scan_thread+0xb4/0xdc
kthread+0x12c/0x13c
ret_from_fork+0x10/0x18
Code:
d503201f f9400660 36000040 d1000413 (
f9400661)
---[ end trace
4d4bd7f573490c8e ]---
Kernel panic - not syncing: Fatal exception
SMP: stopping secondary CPUs
Kernel Offset: disabled
CPU features: 0x002,
20000c38
Memory Limit: none
---[ end Kernel panic - not syncing: Fatal exception ]---
Link: http://lkml.kernel.org/r/20190122132916.28360-1-cai@lca.pw
Fixes:
9f1eb38e0e11 ("mm, kmemleak: little optimization while scanning")
Signed-off-by: Qian Cai <cai@lca.pw>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* walkers which rely on the fully initialized page->flags and others
* should use this rather than pfn_valid && pfn_to_page
*/
-#define pfn_to_online_page(pfn) \
-({ \
- struct page *___page = NULL; \
- unsigned long ___nr = pfn_to_section_nr(pfn); \
- \
- if (___nr < NR_MEM_SECTIONS && online_section_nr(___nr))\
- ___page = pfn_to_page(pfn); \
- ___page; \
+#define pfn_to_online_page(pfn) \
+({ \
+ struct page *___page = NULL; \
+ unsigned long ___pfn = pfn; \
+ unsigned long ___nr = pfn_to_section_nr(___pfn); \
+ \
+ if (___nr < NR_MEM_SECTIONS && online_section_nr(___nr) && \
+ pfn_valid_within(___pfn)) \
+ ___page = pfn_to_page(___pfn); \
+ ___page; \
})
/*