[patch V5 01/32] mm/slab: Remove broken stack trace storage

Thomas Gleixner
2019-04-16T14:10:33Z

kstack_end() is broken on interrupt stacks as they are not guaranteed to be
sized THREAD_SIZE and THREAD_SIZE aligned.

As SLAB seems not to be used much with debugging enabled and might just go
away completely according to:

https://lkml.kernel.org/r/612f9b99-a75b-6aeb-cf92-7dc5421cd950@suse.cz

just remove the bogus code instead of trying to fix it.

Fixes: 98eb235b7feb ("[PATCH] page unmapping debug") - History tree
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: linux-mm@kvack.org
---
V5: Remove the cruft.
V4: Make it actually work
V2: Made the code simpler to understand (Andy)
---
mm/slab.c | 22 +++-------------------
1 file changed, 3 insertions(+), 19 deletions(-)

--- a/mm/slab.c
+++ b/mm/slab.c
@@ -1470,33 +1470,17 @@ static bool is_debug_pagealloc_cache(str
static void store_stackinfo(struct kmem_cache *cachep, unsigned long *addr,
unsigned long caller)
{
- int size = cachep->object_size;
+ int size = cachep->object_size / sizeof(unsigned long);

addr = (unsigned long *)&((char *)addr)[obj_offset(cachep)];

- if (size < 5 * sizeof(unsigned long))
+ if (size < 4)
return;

*addr++ = 0x12345678;
*addr++ = caller;
*addr++ = smp_processor_id();
- size -= 3 * sizeof(unsigned long);
- {
- unsigned long *sptr = &caller;
- unsigned long svalue;
-
- while (!kstack_end(sptr)) {
- svalue = *sptr++;
- if (kernel_text_address(svalue)) {
- *addr++ = svalue;
- size -= sizeof(unsigned long);
- if (size <= sizeof(unsigned long))
- break;
- }
- }
-
- }
- *addr++ = 0x87654321;
+ *addr = 0x87654321;
}

static void slab_kernel_map(struct kmem_cache *cachep, void *objp,