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t=1784530535; bh=ked3BDcGYDpvXw7eNGYa4GCDwM9ERmQ/SIgaGlKW6Ck=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=LFg3vQ0zClOXjP/YUj6Ru9ICRSn7R1j2oqc4shwEXq3xguWXJodF6dFMpacxMyFGc pz/BCAWzVAGCiG+GAGZLNhsWmUkDYrTRnW+lnnfD2t7IRdELSniFNhjpuDPZIL11dI JNFPa9hnzLEBCDSVV+JinCyuAVIxGA1op3SJ2GhY= From: Dev Jain To: akpm@linux-foundation.org, david@kernel.org, ljs@kernel.org Cc: Dev Jain , kasong@tencent.com, qi.zheng@linux.dev, shakeel.butt@linux.dev, baohua@kernel.org, axelrasmussen@google.com, yuanchu@google.com, weixugc@google.com, liam@infradead.org, vbabka@kernel.org, rppt@kernel.org, surenb@google.com, mhocko@suse.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org, riel@surriel.com, harry@kernel.org, jannh@google.com, lance.yang@linux.dev, ryan.roberts@arm.com, anshuman.khandual@arm.com Subject: [PATCH v2 2/3] mm/memory: batch set uffd-wp markers during zapping Date: Mon, 20 Jul 2026 06:55:06 +0000 Message-ID: <20260720065508.2695106-3-dev.jain@arm.com> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20260720065508.2695106-1-dev.jain@arm.com> References: <20260720065508.2695106-1-dev.jain@arm.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Rspamd-Server: rspam06 X-Rspamd-Queue-Id: 32251A0007 X-Stat-Signature: e1dmdgqg6x1beof3hhh15z1p511ajb39 X-Rspam-User: X-HE-Tag: 1784530536-420254 X-HE-Meta: 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 PbQJtngN pH1H6r0s8VxjqzU9m5SrtvMFtV/jJh9JngFkIoh6LwpR2gzzIbUiOkkOwwqEW5ypq7mIy2FnROkxK9jFMzS18jks/iUSiwk6DY7zoLQA089Gszzljfyl94OmzcEw9rEwMrjPeFgWuF1KdGtVUpXNIfBoOcveqGVmI/rtKEWZQig3zYnjI6TYA7pTxzS5enXvvjzF9bcwc7RxsAQX92ulimbNkTp/UulUVTX0Y6PYB3rOvKjeIOtcCgWERpw== Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: Enable batch setting of uffd-wp PTE markers. The code paths passing nr > 1 to zap_install_uffd_wp_if_needed() produce that nr through either folio_pte_batch() or swap_pte_batch(), therefore batching is correct: 1) All PTEs belong to the same type of VMA: anonymous or non-anonymous, wp-armed or non-wp-armed. 2) All PTEs are either marked with uffd-wp or not marked with uffd-wp; the same applies to the pte_swp_uffd_any() check. 3) uffd_supports_wp_marker() is independent of the function parameters. Use set_pte_at() in a loop instead of set_ptes(), because set_ptes() cannot handle nonpresent to nonpresent conversion for nr_pages > 1. Rename the helper to cond_install_uffd_wp_ptes(). Signed-off-by: Dev Jain --- mm/internal.h | 5 +++-- mm/memory.c | 61 +++++++++++++++++++++------------------------------ mm/rmap.c | 2 +- 3 files changed, 29 insertions(+), 39 deletions(-) diff --git a/mm/internal.h b/mm/internal.h index b6a3589a61c1a..0f49cff67a2b8 100644 --- a/mm/internal.h +++ b/mm/internal.h @@ -276,8 +276,9 @@ void unmap_vmas(struct mmu_gather *tlb, struct unmap_desc *unmap); #ifdef CONFIG_MMU -bool pte_install_uffd_wp_if_needed(struct vm_area_struct *vma, - unsigned long addr, pte_t *ptep, pte_t pte); +bool cond_install_uffd_wp_ptes(struct vm_area_struct *vma, + unsigned long addr, pte_t *ptep, pte_t pte, + unsigned long nr_ptes); static inline void get_anon_vma(struct anon_vma *anon_vma) { diff --git a/mm/memory.c b/mm/memory.c index 6c0c4c774674a..d2f14ba2261cd 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -1676,27 +1676,29 @@ static inline bool zap_drop_markers(struct zap_details *details) } /** - * pte_install_uffd_wp_if_needed - install uffd-wp marker after clearing a PTE - * @vma: The VMA the page is mapped into. - * @addr: Address the page is mapped at. - * @ptep: Page table pointer for this entry. + * cond_install_uffd_wp_ptes - install uffd-wp markers after clearing PTEs + * @vma: The VMA the pages are mapped into. + * @addr: Address the first page of this batch is mapped at. + * @ptep: Page table pointer for the first entry of this batch. * @pte: Old value of the entry pointed to by @ptep. + * @nr_ptes: Number of entries to install. * - * If the PTE was write-protected by uffd-wp in any form, arm a special PTE - * to replace a none PTE. NOTE! This should only be called when the PTE is + * If the PTEs were write-protected by uffd-wp in any form, arm special PTEs + * to replace none PTEs. NOTE! This should only be called when the PTEs are * already cleared so we will never accidentally replace something valuable. - * Meanwhile none PTEs also mean we are not demoting the PTE so a TLB flush is - * not needed. E.g., when the PTE was cleared, the caller should have taken care - * of the TLB flush. + * Meanwhile none PTEs also mean we are not demoting the PTEs so a TLB flush is + * not needed. E.g., when the PTEs were cleared, the caller should have taken + * care of the TLB flush. * * Must be called with the page table lock held so that no thread will see the - * none PTE, and if they see it, they'll fault and serialize at the page table + * none PTEs, and if they see them, they'll fault and serialize at the page table * lock. * - * Returns true if an uffd-wp PTE was installed, false otherwise. + * Returns true if uffd-wp PTEs were installed, false otherwise. */ -bool pte_install_uffd_wp_if_needed(struct vm_area_struct *vma, - unsigned long addr, pte_t *ptep, pte_t pte) +bool cond_install_uffd_wp_ptes(struct vm_area_struct *vma, + unsigned long addr, pte_t *ptep, pte_t pte, + unsigned long nr_ptes) { bool arm_uffd_pte = false; @@ -1726,13 +1728,19 @@ bool pte_install_uffd_wp_if_needed(struct vm_area_struct *vma, if (unlikely(pte_swp_uffd_any(pte))) arm_uffd_pte = true; - if (unlikely(arm_uffd_pte)) { + if (likely(!arm_uffd_pte)) + return false; + + for (;;) { set_pte_at(vma->vm_mm, addr, ptep, make_pte_marker(PTE_MARKER_UFFD_WP)); - return true; + if (--nr_ptes == 0) + break; + ptep++; + addr += PAGE_SIZE; } - return false; + return true; } /* @@ -1746,29 +1754,10 @@ zap_install_uffd_wp_if_needed(struct vm_area_struct *vma, unsigned long addr, pte_t *pte, int nr, struct zap_details *details, pte_t pteval) { - bool was_installed = false; - - if (!uffd_supports_wp_marker()) - return false; - - /* Zap on anonymous always means dropping everything */ - if (vma_is_anonymous(vma)) - return false; - if (zap_drop_markers(details)) return false; - for (;;) { - /* the PFN in the PTE is irrelevant. */ - if (pte_install_uffd_wp_if_needed(vma, addr, pte, pteval)) - was_installed = true; - if (--nr == 0) - break; - pte++; - addr += PAGE_SIZE; - } - - return was_installed; + return cond_install_uffd_wp_ptes(vma, addr, pte, pteval, nr); } static __always_inline void zap_present_folio_ptes(struct mmu_gather *tlb, diff --git a/mm/rmap.c b/mm/rmap.c index 73c2fe2d19462..abeb8e7ceba17 100644 --- a/mm/rmap.c +++ b/mm/rmap.c @@ -2348,7 +2348,7 @@ static bool try_to_unmap_one(struct folio *folio, struct vm_area_struct *vma, * we may want to replace a none pte with a marker pte if * it's file-backed, so we don't lose the tracking info. */ - pte_install_uffd_wp_if_needed(vma, address, pvmw.pte, pteval); + cond_install_uffd_wp_ptes(vma, address, pvmw.pte, pteval, 1); /* Update high watermark before we lower rss */ update_hiwater_rss(mm); -- 2.43.0