Re: [Crash-utility] [PATCH 1/2] Fix cpu_slab freelist handling on SLUB
Dave Anderson <anderson(a)redhat.com> writes:
----- Original Message -----
> OGAWA Hirofumi <hirofumi(a)mail.parknet.co.jp> writes:
>
> OK. More simpler proof, the following is enough to convince you?
[...]
But going back to the error report, the "slab: 0" is kind
of confusing:
crash> kmem -s kmalloc-32
CACHE NAME OBJSIZE ALLOCATED TOTAL SLABS SSIZE
kmem: kmalloc-32: slab: 0 invalid freepointer: ffff001090e33f80
ffff880333001c00 kmalloc-32 32 122658 125440 980 4k
crash>
[...]
I'm thinking we should clarify that error message, perhaps by
storing the cpu
number in si->cpu, and displaying it when si->slab is NULL?
Just a idea for now though (means not tested error path at all), how
about the following?
We know already slab pointer at that point. So, this sets si->slab
temporarily. (and slub_page_objects() just uses slab in argument, not
si->slab).
Thanks.
---
memory.c | 23 +++++++++++++++++------
1 file changed, 17 insertions(+), 6 deletions(-)
diff -puN memory.c~crash-slub-freelist-error-fix memory.c
--- crash-64/memory.c~crash-slub-freelist-error-fix 2016-04-21 05:04:11.660627253 +0900
+++ crash-64-hirofumi/memory.c 2016-04-21 05:20:01.673010107 +0900
@@ -17947,12 +17947,12 @@ static ushort slub_page_objects(struct m
if (CRASHDEBUG(1) && (objects != si->objects))
error(NOTE, "%s: slab: %lx oo objects: %ld "
"slab objects: %d\n",
- si->curname, si->slab,
+ si->curname, page,
si->objects, objects);
if (objects == (ushort)(-1)) {
error(INFO, "%s: slab: %lx invalid page.objects: -1\n",
- si->curname, si->slab);
+ si->curname, page);
return 0;
}
} else
@@ -18039,14 +18039,22 @@ get_kmem_cache_slub_data(long cmd, struc
switch (cmd)
{
- case GET_SLUB_OBJECTS:
+ case GET_SLUB_OBJECTS: {
+ /* For better error report, set cur slab to si->slab. */
+ ulong orig_slab = si->slab;
+ si->slab = cpu_slab_ptr;
+
if (!readmem(cpu_slab_ptr + OFFSET(page_inuse),
- KVADDR, &inuse, sizeof(short),
- "page inuse", RETURN_ON_ERROR))
+ KVADDR, &inuse, sizeof(short),
+ "page inuse", RETURN_ON_ERROR)) {
+ si->slab = orig_slab;
return FALSE;
+ }
objects = slub_page_objects(si, cpu_slab_ptr);
- if (!objects)
+ if (!objects) {
+ si->slab = orig_slab;
return FALSE;
+ }
free_objects += objects - inuse;
free_objects += count_free_objects(si, cpu_freelist);
@@ -18055,6 +18063,9 @@ get_kmem_cache_slub_data(long cmd, struc
if (!node_total_avail)
total_objects += inuse;
total_slabs++;
+
+ si->slab = orig_slab;
+ }
break;
case GET_SLUB_SLABS:
_
--
OGAWA Hirofumi <hirofumi(a)mail.parknet.co.jp>