| lists.openwall.net | lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC | |
|
Open Source and information security mailing list archives
| ||
|
Message-ID: <fe8f9d0e-3c79-449c-98ae-7134ffbb7ffd@arm.com>
Date: Thu, 5 Sep 2024 15:23:24 +0530
From: Dev Jain <dev.jain@....com>
To: Kefeng Wang <wangkefeng.wang@...wei.com>,
"Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>
Cc: akpm@...ux-foundation.org, david@...hat.com, willy@...radead.org,
ryan.roberts@....com, anshuman.khandual@....com, catalin.marinas@....com,
cl@...two.org, vbabka@...e.cz, mhocko@...e.com, apopple@...dia.com,
dave.hansen@...ux.intel.com, will@...nel.org, baohua@...nel.org,
jack@...e.cz, mark.rutland@....com, hughd@...gle.com,
aneesh.kumar@...nel.org, yang@...amperecomputing.com, peterx@...hat.com,
ioworker0@...il.com, jglisse@...gle.com,
linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
linux-mm@...ck.org
Subject: Re: [PATCH v2 2/2] mm: Allocate THP on hugezeropage wp-fault
On 9/5/24 15:11, Kefeng Wang wrote:
>
>
> On 2024/9/5 16:26, Kirill A. Shutemov wrote:
>> On Wed, Sep 04, 2024 at 03:39:23PM +0530, Dev Jain wrote:
>>> Introduce do_huge_zero_wp_pmd() to handle wp-fault on a hugezeropage
>>> and
>>> replace it with a PMD-mapped THP. Change the helpers introduced in the
>>> previous patch to flush TLB entry corresponding to the hugezeropage,
>>> and preserve PMD uffd-wp marker. In case of failure, fallback to
>>> splitting the PMD.
>
> We met same issue, and a very similar function in our kernel,
>>>
>>> Signed-off-by: Dev Jain <dev.jain@....com>
>>> ---
>>> include/linux/huge_mm.h | 6 ++++
>>> mm/huge_memory.c | 79
>>> +++++++++++++++++++++++++++++++++++------
>>> mm/memory.c | 5 +--
>>> 3 files changed, 78 insertions(+), 12 deletions(-)
>>>
>>> diff --git a/include/linux/huge_mm.h b/include/linux/huge_mm.h
>>> index e25d9ebfdf89..fdd2cf473a3c 100644
>>> --- a/include/linux/huge_mm.h
>>> +++ b/include/linux/huge_mm.h
>>> @@ -9,6 +9,12 @@
>>> #include <linux/kobject.h>
>>> vm_fault_t do_huge_pmd_anonymous_page(struct vm_fault *vmf);
>>> +vm_fault_t thp_fault_alloc(gfp_t gfp, int order, struct
>>> vm_area_struct *vma,
>>> + unsigned long haddr, struct folio **foliop,
>>> + unsigned long addr);
>>> +void map_pmd_thp(struct folio *folio, struct vm_fault *vmf,
>>> + struct vm_area_struct *vma, unsigned long haddr,
>>> + pgtable_t pgtable);
>>
>> Why? I don't see users outside huge_memory.c.
>>
>>> int copy_huge_pmd(struct mm_struct *dst_mm, struct mm_struct *src_mm,
>>> pmd_t *dst_pmd, pmd_t *src_pmd, unsigned long addr,
>>> struct vm_area_struct *dst_vma, struct vm_area_struct
>>> *src_vma);
>>> diff --git a/mm/huge_memory.c b/mm/huge_memory.c
>>> index 58125fbcc532..150163ad77d3 100644
>>> --- a/mm/huge_memory.c
>>> +++ b/mm/huge_memory.c
>>> @@ -943,9 +943,9 @@ unsigned long thp_get_unmapped_area(struct file
>>> *filp, unsigned long addr,
>>> }
>>> EXPORT_SYMBOL_GPL(thp_get_unmapped_area);
>>> -static vm_fault_t thp_fault_alloc(gfp_t gfp, int order, struct
>>> vm_area_struct *vma,
>>> - unsigned long haddr, struct folio **foliop,
>>> - unsigned long addr)
>>> +vm_fault_t thp_fault_alloc(gfp_t gfp, int order, struct
>>> vm_area_struct *vma,
>>> + unsigned long haddr, struct folio **foliop,
>>> + unsigned long addr)
>>> {
>>> struct folio *folio = vma_alloc_folio(gfp, order, vma, haddr,
>>> true);
>>> @@ -984,21 +984,29 @@ static void __thp_fault_success_stats(struct
>>> vm_area_struct *vma, int order)
>>> count_memcg_event_mm(vma->vm_mm, THP_FAULT_ALLOC);
>>> }
>>> -static void map_pmd_thp(struct folio *folio, struct vm_fault *vmf,
>>> - struct vm_area_struct *vma, unsigned long haddr,
>>> - pgtable_t pgtable)
>>> +void map_pmd_thp(struct folio *folio, struct vm_fault *vmf,
>>> + struct vm_area_struct *vma, unsigned long haddr,
>>> + pgtable_t pgtable)
>>> {
>>> - pmd_t entry;
>>> + pmd_t entry, old_pmd;
>>> + bool is_pmd_none = pmd_none(*vmf->pmd);
>>> entry = mk_huge_pmd(&folio->page, vma->vm_page_prot);
>>> entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma);
>>> folio_add_new_anon_rmap(folio, vma, haddr, RMAP_EXCLUSIVE);
>>> folio_add_lru_vma(folio, vma);
>>> - pgtable_trans_huge_deposit(vma->vm_mm, vmf->pmd, pgtable);
>>> + if (!is_pmd_none) {
>>> + old_pmd = pmdp_huge_clear_flush(vma, haddr, vmf->pmd);
>>> + if (pmd_uffd_wp(old_pmd))
>>> + entry = pmd_mkuffd_wp(entry);
>>> + }
>>> + if (pgtable)
>>> + pgtable_trans_huge_deposit(vma->vm_mm, vmf->pmd, pgtable);
>>> set_pmd_at(vma->vm_mm, haddr, vmf->pmd, entry);
>>> update_mmu_cache_pmd(vma, vmf->address, vmf->pmd);
>>> add_mm_counter(vma->vm_mm, MM_ANONPAGES, HPAGE_PMD_NR);
>>> - mm_inc_nr_ptes(vma->vm_mm);
>>> + if (is_pmd_none)
>>> + mm_inc_nr_ptes(vma->vm_mm);
>>> }
>>> static vm_fault_t __do_huge_pmd_anonymous_page(struct vm_fault
>>> *vmf)
>>> @@ -1576,6 +1584,50 @@ void huge_pmd_set_accessed(struct vm_fault *vmf)
>>> spin_unlock(vmf->ptl);
>>> }
>>> +static vm_fault_t do_huge_zero_wp_pmd_locked(struct vm_fault *vmf,
>>> + unsigned long haddr,
>>> + struct folio *folio)
>>
>> Why the helper is needed? Cannot it be just opencodded in
>> do_huge_zero_wp_pmd()?
>>
>>> +{
>>> + struct vm_area_struct *vma = vmf->vma;
>>> + vm_fault_t ret = 0;
>>> +
>>> + ret = check_stable_address_space(vma->vm_mm);
>>> + if (ret)
>>> + goto out;
>>> + map_pmd_thp(folio, vmf, vma, haddr, NULL);
>>> +out:
>>> + return ret;
>>> +}
>>> +
>>> +static vm_fault_t do_huge_zero_wp_pmd(struct vm_fault *vmf,
>>> unsigned long haddr)
>>> +{
>>> + struct vm_area_struct *vma = vmf->vma;
>>> + gfp_t gfp = vma_thp_gfp_mask(vma);
>>> + struct mmu_notifier_range range;
>>> + struct folio *folio = NULL;
>>> + vm_fault_t ret = 0;
>>> +
>>> + ret = thp_fault_alloc(gfp, HPAGE_PMD_ORDER, vma, haddr, &folio,
>>> + vmf->address);
>>> + if (ret)
>>> + goto out;
>>> +
>>> + mmu_notifier_range_init(&range, MMU_NOTIFY_CLEAR, 0,
>>> vma->vm_mm, haddr,
>>> + haddr + HPAGE_PMD_SIZE);
>>> + mmu_notifier_invalidate_range_start(&range);
>>> + vmf->ptl = pmd_lock(vma->vm_mm, vmf->pmd);
>>> + if (unlikely(!pmd_same(pmdp_get(vmf->pmd), vmf->orig_pmd)))
>>> + goto unlock;
>>> + ret = do_huge_zero_wp_pmd_locked(vmf, haddr, folio);
>>> + if (!ret)
>>> + __thp_fault_success_stats(vma, HPAGE_PMD_ORDER);
>>> +unlock:
>>> + spin_unlock(vmf->ptl);
>>> + mmu_notifier_invalidate_range_end(&range);
>
> the folio need to released when !pmd_same() and
> check_stable_address_space() return VM_FAULT_SIGBUS.
Yes, thanks.
>
>>> +out:
>>> + return ret;
>>> +}
>>> +
>>>
>>
Powered by blists - more mailing lists