Re: [PATCH] mm/slab: improve kmem_cache_alloc_bulk

Harry Yoo <[email protected]> Thu, 4 Jun 2026 16:10:08 +0900

Newsgroups	org.kernel.vger.io-uring,org.freedesktop.lists.dri-devel,org.kernel.vger.bpf,org.kernel.vger.linux-arm-msm,org.kernel.vger.linux-kernel,org.kernel.vger.netdev,org.kvack.linux-mm
Message-ID	<[email protected]>


On 6/4/26 1:22 AM, Vlastimil Babka (SUSE) wrote:
> On 6/3/26 13:13, Rob Clark wrote:
>> On Wed, Jun 3, 2026 at 2:17 AM Vlastimil Babka (SUSE) <[email protected]> wrote:
>>>
>>> We know p->pages is NULL in this case, right? Because it was allocated by
>>> vm_bind_job_create() using kzalloc().
>>> And the job can't be reused with a leftover value?
>>> (msm_iommu_pagetable_prealloc_cleanup doesn't set p->pages to zero).
>>> Or should we set p->pages to NULL here.
>>
>> Correct, the job is not reused.  But I suppose setting p->pages to
>> NULL would make things more obvious, so no objection to that.
> 
> OK, did that, just in case. Thanks.

The kvfree() -> kfree() part should probably be a separate patch
with Fixes: 830d68f2cb8a ("drm/msm: Fix pgtable prealloc error
path") and Cc: stable?

...as the commit landed v6.18.

>> BR,
>> -R
>>
>>>> +
>>>>         p->pages = kvmalloc_objs(*p->pages, p->count);
>>>>         if (!p->pages)
>>>>                 return -ENOMEM;
>>>>
>>>>         ret = kmem_cache_alloc_bulk(pt_cache, GFP_KERNEL, p->count, p->pages);
>>>>         if (ret != p->count) {
>>>> -               kfree(p->pages);
>>>> +               kvfree(p->pages);
>>>>                 p->pages = NULL;
>>>>                 p->count = ret;
>>>>                 return -ENOMEM;

-- 
Cheers,
Harry / Hyeonggon

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