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charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit X-Rspamd-Server: rspam07 X-Rspamd-Queue-Id: BA5431C0006 X-Stat-Signature: sscbcaonw3nkrf1159maqoy1bqy4cr8x X-Rspam-User: X-HE-Tag: 1727242284-475284 X-HE-Meta: U2FsdGVkX1/nzkM1W6ZzxsWsxjwzJGTK51szxwFhCLRJ50U8tcrTWPCSOWqSps/8iuTxSnflD9Jw30NXqjcdEbM/8KN+tZ5otSvEChtabgU5nMFBv+0R0wtUGnGa4Fp/NOEh7j0nB/3GDp9DFKvBmQkabVHDCRGg6lqNv1n92q+tg+Cpy7noZzGJEtpkMwLbDvChq4LProifOjHe/QQtxEGu23MUCtEUF6b5f6OAGoVdZDECIN8CM8REoCILkCLDDnxCwlpepM28Ve4PBxB8d2DTLgk5oAHGGFzOELmZRbbKOnHgKEmh2d1gD/Pmr0R1Q0iF6j/+WWAiE9aW9XZi6iOh7EqkAHL4BoAFe1MHMo9iSY/0xt2287oS8+YMc/fQ+T78V49EWXu4KJ+ybJ6XOzHCLObWAEVeBRcsNrbU4LdyyUzFVKWXnS3kwb9lj/I/H+/zZYJWlUSSBfhk4lMXms0vQfU630A6pfT8hVKcuyHJ7OkgqoZOB+DAK3n23b+BQ4ZhupmuDHlhMjQCx8DmTlvZ29DboqCV0cz9kkGo3bwMDIqwDux122s/wQQkBN0le2RCVH0c4r7FklFUsnVv0dM3iWX1Ixlo+ppn2m0Vc93N/QTSJudbTukZvvhNjO3wYSepUdOn/IRp4mROKj8YoN46n6zo263CRePhBuxiaT/SQhtbFiO9peUsxRkVb3iRJzz6HhrWHqW+rD2Iben0u1KDz+adT597QqfPQjMeOF33iscm2Bb/xxI+5BYkKyhcj5tjMaWNpodocfH0bfKByC1t/+wQTs8Y72Af7xt/dgm1a2QUwcL+NiGx/09+Y/QOfAJTOEEcb4QZ+/nh5K1ufYHFh41IEptaEkAwNm+xCU3Jd4wRwVpqvzStAco5UuWwjGjvGE1IjNfcCDk9NWQikGrhu5r8WEKpd6LcU1+aqc33zpS8q+dZHwONVcvxsPJ3VVTKUzVv7EKRKImWujR bqKZVgW6 3Yigds1FqRJ9YH9N32gOuKaVEiMp5YEwLPIv2lpspQ1gCHE8FmPpjyamc3IjLlAq2kkytGw2MfdI+4yt/rmJxS9y5Gp7n/5Qey7iMPp+v+Y+wie/Bd7glIrUkxp5CXfDQaqkAZnIAcPPN1Zogdr14DthxErEScYNd6gIjnLfPSEQ/y8ibfoz4S32zdiSjeUytbI45IxBzVh/nM9irI2G2EbqsqYsX3sPEC6jDNc/1/3Q923YJxulT11y2FUO3e2B97Xhq X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 9/24/24 18:43, Kefeng Wang wrote: > > > On 2024/9/24 18:16, Dev Jain wrote: >> Introduce do_huge_zero_wp_pmd() to handle wp-fault on a hugezeropage and >> replace it with a PMD-mapped THP. Remember to flush TLB entry >> corresponding to the hugezeropage. In case of failure, fallback >> to splitting the PMD. >> >> Signed-off-by: Dev Jain >> --- >>   mm/huge_memory.c | 44 +++++++++++++++++++++++++++++++++++++++++++- >>   1 file changed, 43 insertions(+), 1 deletion(-) >> >> diff --git a/mm/huge_memory.c b/mm/huge_memory.c >> index bdbf67c18f6c..fbb195bc2038 100644 >> --- a/mm/huge_memory.c >> +++ b/mm/huge_memory.c >> @@ -1790,6 +1790,41 @@ void huge_pmd_set_accessed(struct vm_fault *vmf) >>       spin_unlock(vmf->ptl); >>   } >>   +static vm_fault_t do_huge_zero_wp_pmd(struct vm_fault *vmf) >> +{ >> +    unsigned long haddr = vmf->address & HPAGE_PMD_MASK; >> +    struct vm_area_struct *vma = vmf->vma; >> +    struct mmu_notifier_range range; >> +    struct folio *folio; >> +    vm_fault_t ret = 0; >> + >> +    folio = vma_alloc_anon_folio_pmd(vma, vmf->address); >> +    if (unlikely(!folio)) { >> +        ret = VM_FAULT_FALLBACK; > > I'd like to return VM_FAULT_FALLBACK if you re-post. That's cleaner. I need to keep my "goto" obsession in control... > > Reviewed-by: Kefeng Wang Thanks! > >> +        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 release; >> +    ret = check_stable_address_space(vma->vm_mm); >> +    if (ret) >> +        goto release; >> +    (void)pmdp_huge_clear_flush(vma, haddr, vmf->pmd); >> +    map_anon_folio_pmd(folio, vmf->pmd, vma, haddr); >> +    goto unlock; >> +release: >> +    folio_put(folio); >> +unlock: >> +    spin_unlock(vmf->ptl); >> +    mmu_notifier_invalidate_range_end(&range); >> +out: >> +    return ret; >> +} >> + >>   vm_fault_t do_huge_pmd_wp_page(struct vm_fault *vmf) >>   { >>       const bool unshare = vmf->flags & FAULT_FLAG_UNSHARE; >> @@ -1802,8 +1837,15 @@ vm_fault_t do_huge_pmd_wp_page(struct vm_fault >> *vmf) >>       vmf->ptl = pmd_lockptr(vma->vm_mm, vmf->pmd); >>       VM_BUG_ON_VMA(!vma->anon_vma, vma); >>   -    if (is_huge_zero_pmd(orig_pmd)) >> +    if (is_huge_zero_pmd(orig_pmd)) { >> +        vm_fault_t ret = do_huge_zero_wp_pmd(vmf); >> + >> +        if (!(ret & VM_FAULT_FALLBACK)) >> +            return ret; >> + >> +        /* Fallback to splitting PMD if THP cannot be allocated */ >>           goto fallback; >> +    } >>         spin_lock(vmf->ptl); > >