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SubjectRe: [PATCH] slab: remove store_stackinfo()
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On 4/16/19 4:22 PM, Qian Cai wrote:
> store_stackinfo() does not seem used in actual SLAB debugging.
> Potentially, it could be added to check_poison_obj() to provide more
> information, but this seems like an overkill due to the declining
> popularity of the SLAB, so just remove it instead.
>
> Signed-off-by: Qian Cai <cai@lca.pw>

I've acked Thomas' version already which was narrower, but no objection
to remove more stuff on top of that. Linus (and I later in another
thread) already pointed out /proc/slab_allocators. It only takes a look
at add_caller() there to not regret removing that one.

> ---
> mm/slab.c | 48 ++++++------------------------------------------
> 1 file changed, 6 insertions(+), 42 deletions(-)
>
> diff --git a/mm/slab.c b/mm/slab.c
> index 3e1b7ff0360c..20f318f4f56e 100644
> --- a/mm/slab.c
> +++ b/mm/slab.c
> @@ -1467,53 +1467,17 @@ static bool is_debug_pagealloc_cache(struct kmem_cache *cachep)
> }
>
> #ifdef CONFIG_DEBUG_PAGEALLOC
> -static void store_stackinfo(struct kmem_cache *cachep, unsigned long *addr,
> - unsigned long caller)
> -{
> - int size = cachep->object_size;
> -
> - addr = (unsigned long *)&((char *)addr)[obj_offset(cachep)];
> -
> - if (size < 5 * sizeof(unsigned long))
> - 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;
> -}
> -
> -static void slab_kernel_map(struct kmem_cache *cachep, void *objp,
> - int map, unsigned long caller)
> +static void slab_kernel_map(struct kmem_cache *cachep, void *objp, int map)
> {
> if (!is_debug_pagealloc_cache(cachep))
> return;
>
> - if (caller)
> - store_stackinfo(cachep, objp, caller);
> -
> kernel_map_pages(virt_to_page(objp), cachep->size / PAGE_SIZE, map);
> }
>
> #else
> static inline void slab_kernel_map(struct kmem_cache *cachep, void *objp,
> - int map, unsigned long caller) {}
> + int map) {}
>
> #endif
>
> @@ -1661,7 +1625,7 @@ static void slab_destroy_debugcheck(struct kmem_cache *cachep,
>
> if (cachep->flags & SLAB_POISON) {
> check_poison_obj(cachep, objp);
> - slab_kernel_map(cachep, objp, 1, 0);
> + slab_kernel_map(cachep, objp, 1);
> }
> if (cachep->flags & SLAB_RED_ZONE) {
> if (*dbg_redzone1(cachep, objp) != RED_INACTIVE)
> @@ -2433,7 +2397,7 @@ static void cache_init_objs_debug(struct kmem_cache *cachep, struct page *page)
> /* need to poison the objs? */
> if (cachep->flags & SLAB_POISON) {
> poison_obj(cachep, objp, POISON_FREE);
> - slab_kernel_map(cachep, objp, 0, 0);
> + slab_kernel_map(cachep, objp, 0);
> }
> }
> #endif
> @@ -2812,7 +2776,7 @@ static void *cache_free_debugcheck(struct kmem_cache *cachep, void *objp,
>
> if (cachep->flags & SLAB_POISON) {
> poison_obj(cachep, objp, POISON_FREE);
> - slab_kernel_map(cachep, objp, 0, caller);
> + slab_kernel_map(cachep, objp, 0);
> }
> return objp;
> }
> @@ -3076,7 +3040,7 @@ static void *cache_alloc_debugcheck_after(struct kmem_cache *cachep,
> return objp;
> if (cachep->flags & SLAB_POISON) {
> check_poison_obj(cachep, objp);
> - slab_kernel_map(cachep, objp, 1, 0);
> + slab_kernel_map(cachep, objp, 1);
> poison_obj(cachep, objp, POISON_INUSE);
> }
> if (cachep->flags & SLAB_STORE_USER)
>

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