Re: [vbabka:b4/sheaves-for-all] [slab] de840681a1: BUG:using_smp_processor_id()in_preemptible

[Vlastimil Babka <vbabka@suse.cz>]

On 10/16/25 08:08, kernel test robot wrote:
> 
> 
> Hello,
> 
> kernel test robot noticed "BUG:using_smp_processor_id()in_preemptible" on:
> 
> commit: de840681a162e0a5a0862e7a0b495fb34deab7ef ("slab: remove cpu (partial) slabs usage from allocation paths")
> https://git.kernel.org/cgit/linux/kernel/git/vbabka/linux.git b4/sheaves-for-all
> 
> in testcase: boot
> 
> config: i386-randconfig-002-20251015
> compiler: gcc-14
> test machine: qemu-system-x86_64 -enable-kvm -cpu SandyBridge -smp 2 -m 16G
> 
> (please refer to attached dmesg/kmsg for entire log/backtrace)
> 
> 
> 
> If you fix the issue in a separate patch/commit (i.e. not just a new version of
> the same patch/commit), kindly add following tags
> | Reported-by: kernel test robot <oliver.sang@intel.com>
> | Closes: https://lore.kernel.org/oe-lkp/202510161416.b7adda58-lkp@intel.com
> 

Thanks, no more disabled preemption so use the raw version as we don't
need it to be stable. Will fold this in:
----8<----
diff --git a/mm/slub.c b/mm/slub.c
index 91e1db412018..cd4b0833fb4a 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -1032,7 +1032,7 @@ static void set_track_update(struct kmem_cache *s, void *object,
        p->handle = handle;
 #endif
        p->addr = addr;
-       p->cpu = smp_processor_id();
+       p->cpu = raw_smp_processor_id();
        p->pid = current->pid;
        p->when = jiffies;
 }
@@ -4481,16 +4481,8 @@ static void *___slab_alloc(struct kmem_cache *s, gfp_t gfpflags, int node,
        pc.orig_size = orig_size;
        freelist = get_partial(s, node, &pc);
        if (freelist) {
-               /*
-                * TODO: check if still applicable
-                *
-                * Due to disabled preemption we need to disallow
-                * blocking. The flags are further adjusted by
-                * gfp_nested_mask() in stack_depot itself.
-                */
                if (kmem_cache_debug_flags(s, SLAB_STORE_USER))
-                       set_track(s, freelist, TRACK_ALLOC, addr,
-                                 gfpflags & ~(__GFP_DIRECT_RECLAIM));
+                       set_track(s, freelist, TRACK_ALLOC, addr, gfpflags);
 
                return freelist;
        }
@@ -4515,8 +4507,7 @@ static void *___slab_alloc(struct kmem_cache *s, gfp_t gfpflags, int node,
                goto new_objects;
 
        if (kmem_cache_debug_flags(s, SLAB_STORE_USER))
-               set_track(s, freelist, TRACK_ALLOC, addr,
-                         gfpflags & ~(__GFP_DIRECT_RECLAIM));
+               set_track(s, freelist, TRACK_ALLOC, addr, gfpflags);
 
        return freelist;
 }
lines 1-41/41 (END)