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t=1784114345; bh=FASJfRiTYqPOAEgL4yWBpkca2p01JpG0G1APx8Od+GI=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=TSyiesxWF+4lR5EXk4mJ8aedDhJdaZr5m6Ev+e3nDI2m73M0OUfsk7FB+lhm5eOtu +ssIUymltMwxLBuDjFjNmuScj5fBtfHkZi6H0MeKLaBRTZhXaitWiZgodxES19d3BN eqw+Zq1ohFviuknmQalmTbW1tD/w//s76UbIdHfk= From: Dev Jain To: akpm@linux-foundation.org, david@kernel.org, ljs@kernel.org Cc: Dev Jain , liam@infradead.org, vbabka@kernel.org, rppt@kernel.org, surenb@google.com, mhocko@suse.com, kasong@tencent.com, qi.zheng@linux.dev, shakeel.butt@linux.dev, baohua@kernel.org, axelrasmussen@google.com, yuanchu@google.com, weixugc@google.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 2/3] mm/memory: batch set uffd-wp markers during zapping Date: Wed, 15 Jul 2026 11:18:35 +0000 Message-ID: <20260715111839.1667914-3-dev.jain@arm.com> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20260715111839.1667914-1-dev.jain@arm.com> References: <20260715111839.1667914-1-dev.jain@arm.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Rspam-User: X-Rspamd-Server: rspam05 X-Rspamd-Queue-Id: 40C6E12000F X-Stat-Signature: 9hjoy8hwnndfoj1e164abrbmswuiag9u X-HE-Tag: 1784114346-690058 X-HE-Meta: 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 74bZ7S2x 3MCarYaHaplcPmAu+h0OCBHxdzPLmIrHjoVARrERGZUQdha63ZhV1oCpMDCQWXf+P6cGru4cqZ5qfCW2gizyB8XNfPfMWk6/l7gIPP+CsQsy2XX4y0HmlgncUKC+bQhWX2xNDdiLrwSzRBSFMIkAXT9pd2hEkxYZCPrhumfV5C8L9FJqpadk/pJ2m6XxWO0mBiueDRvyq9BvbSW5Snmq7tOgMO/wuzaJuKWTsbzMOBqP4imkLD0NaCxIE6g== 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 ptes. 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 being marked with uffd-wp or all being not marked (same is the case with the pte_swp_uffd_wp_any check) 3) uffd_supports_wp_marker() is independent of the function parameters Note that we will have to use set_pte_at() in a loop instead of set_ptes() since the latter cannot handle present->non-present conversion for nr_pages > 1. Rename the function to cond_install_uffd_wp_ptes. Signed-off-by: Dev Jain --- To handle nonpresent->nonpresent transition in the ptes, we can have a set_nonpresent_ptes() (in my unmap series) : if !softleaf_has_pfn(), use set the same pte value to all ptep's in the patch. if softleaf_has_pfn(), then add a softleaf_next_pfn() to construct the next softleaf, and pte_next_softleaf() to call softleaf_next_pfn() and preserve the wp bit, s-d bit, etc from the previous pte. include/linux/mm.h | 6 +++-- mm/memory.c | 64 +++++++++++++++++----------------------------- mm/rmap.c | 2 +- 3 files changed, 29 insertions(+), 43 deletions(-) diff --git a/include/linux/mm.h b/include/linux/mm.h index a71341c44655e..94e0a92bc70b1 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -5406,6 +5406,8 @@ void map_anon_folio_pte_nopf(struct folio *folio, pte_t *pte, struct vm_area_struct *vma, unsigned long addr, bool uffd_wp); -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); + #endif /* _LINUX_MM_H */ diff --git a/mm/memory.c b/mm/memory.c index 98b3ace15cef2..5d2b567b383d4 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 - * 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. + * 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 PTEs so a + * TLB flush is not needed. E.g., when 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 - * lock. + * Must be called with the page table lock held so that no thread will see + * the 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 +1728,14 @@ 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 (unsigned long i = 0; i < nr_ptes; ++i, ++ptep, addr += PAGE_SIZE) set_pte_at(vma->vm_mm, addr, ptep, make_pte_marker(PTE_MARKER_UFFD_WP)); - return true; - } - return false; + return true; } /* @@ -1746,29 +1749,10 @@ 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 ad820fe86f7d8..2f938d0ac6953 100644 --- a/mm/rmap.c +++ b/mm/rmap.c @@ -2345,7 +2345,7 @@ 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