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Thu, 05 Jan 2023 02:19:42 -0800 (PST) Date: Thu, 5 Jan 2023 10:18:31 +0000 In-Reply-To: <20230105101844.1893104-1-jthoughton@google.com> Mime-Version: 1.0 References: <20230105101844.1893104-1-jthoughton@google.com> X-Mailer: git-send-email 2.39.0.314.g84b9a713c41-goog Message-ID: <20230105101844.1893104-34-jthoughton@google.com> Subject: [PATCH 33/46] hugetlb: userfaultfd: add support for high-granularity UFFDIO_CONTINUE From: James Houghton To: Mike Kravetz , Muchun Song , Peter Xu Cc: David Hildenbrand , David Rientjes , Axel Rasmussen , Mina Almasry , "Zach O'Keefe" , Manish Mishra , Naoya Horiguchi , "Dr . David Alan Gilbert" , "Matthew Wilcox (Oracle)" , Vlastimil Babka , Baolin Wang , Miaohe Lin , Yang Shi , Andrew Morton , linux-mm@kvack.org, linux-kernel@vger.kernel.org, James Houghton X-Rspam-User: X-Rspamd-Server: rspam03 X-Rspamd-Queue-Id: C5CFF2000B X-Stat-Signature: r476arzkcoos6i6jhseep53uj84md9zr X-HE-Tag: 1672913982-376914 X-HE-Meta: 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 9vsaa/Sm axJfTQwzQJ5PsJ34gaS3TsRTF1JZWxAqhQPtyrrOO+McK7UDvc7CKaSa9vGUQi1J2Kj0t4V9LqxTdaJ2IaIQXU80xWcSm+x6C6TCOnNJ921u/sIgaFN+L/e7874k781g3jyu2BxVlcfF9j9LJeEncfvO+U0HM93Cm8fVngkGIWj73+QcIRYRq+Ms2DLhGlA1fHO58MeRhBvnWXi2a5srH8dDBV6+xSXkwxcTMumUwLXx7vgBa3MM7IhwfYaRF3XD764kmFGZa5mS4bn+41VGoOoFvFBrMORbbauBXdYfQ0+xRHZ4lL2E/IOVZ06JP8i6ue7YhJvBZSu/yNzvBf9GK2/M58J7phMpcKh/rO1YGuhFCVoL3GUQLaqJmcfD3/8fPdVDSbqIDLNh/NQdXVF+gkzrcLkhSlttoGkIaSKgU7z2EGnejtcvXiEV/1BM/n9GRMxuN 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: Changes here are similar to the changes made for hugetlb_no_page. Pass vmf->real_address to userfaultfd_huge_must_wait because vmf->address may be rounded down to the hugepage size, and a high-granularity page table walk would look up the wrong PTE. Also change the call to userfaultfd_must_wait in the same way for consistency. This commit introduces hugetlb_alloc_largest_pte which is used to find the appropriate PTE size to map pages with UFFDIO_CONTINUE. When MADV_SPLIT is provided, page fault events will report PAGE_SIZE-aligned address instead of huge_page_size(h)-aligned addresses, regardless of if UFFD_FEATURE_EXACT_ADDRESS is used. Signed-off-by: James Houghton --- fs/userfaultfd.c | 14 +++---- include/linux/hugetlb.h | 18 ++++++++- mm/hugetlb.c | 85 +++++++++++++++++++++++++++++++++-------- mm/userfaultfd.c | 40 +++++++++++-------- 4 files changed, 119 insertions(+), 38 deletions(-) diff --git a/fs/userfaultfd.c b/fs/userfaultfd.c index 15a5bf765d43..940ff63096a9 100644 --- a/fs/userfaultfd.c +++ b/fs/userfaultfd.c @@ -252,17 +252,17 @@ static inline bool userfaultfd_huge_must_wait(struct userfaultfd_ctx *ctx, unsigned long flags, unsigned long reason) { - pte_t *ptep, pte; + pte_t pte; bool ret = true; + struct hugetlb_pte hpte; mmap_assert_locked(ctx->mm); - ptep = hugetlb_walk(vma, address, vma_mmu_pagesize(vma)); - if (!ptep) + if (hugetlb_full_walk(&hpte, vma, address)) goto out; ret = false; - pte = huge_ptep_get(ptep); + pte = huge_ptep_get(hpte.ptep); /* * Lockless access: we're in a wait_event so it's ok if it @@ -531,11 +531,11 @@ vm_fault_t handle_userfault(struct vm_fault *vmf, unsigned long reason) spin_unlock_irq(&ctx->fault_pending_wqh.lock); if (!is_vm_hugetlb_page(vma)) - must_wait = userfaultfd_must_wait(ctx, vmf->address, vmf->flags, - reason); + must_wait = userfaultfd_must_wait(ctx, vmf->real_address, + vmf->flags, reason); else must_wait = userfaultfd_huge_must_wait(ctx, vma, - vmf->address, + vmf->real_address, vmf->flags, reason); if (is_vm_hugetlb_page(vma)) hugetlb_vma_unlock_read(vma); diff --git a/include/linux/hugetlb.h b/include/linux/hugetlb.h index 8a664a9dd0a8..c8524ac49b24 100644 --- a/include/linux/hugetlb.h +++ b/include/linux/hugetlb.h @@ -224,7 +224,8 @@ unsigned long hugetlb_total_pages(void); vm_fault_t hugetlb_fault(struct mm_struct *mm, struct vm_area_struct *vma, unsigned long address, unsigned int flags); #ifdef CONFIG_USERFAULTFD -int hugetlb_mcopy_atomic_pte(struct mm_struct *dst_mm, pte_t *dst_pte, +int hugetlb_mcopy_atomic_pte(struct mm_struct *dst_mm, + struct hugetlb_pte *dst_hpte, struct vm_area_struct *dst_vma, unsigned long dst_addr, unsigned long src_addr, @@ -1292,16 +1293,31 @@ static inline enum hugetlb_level hpage_size_to_level(unsigned long sz) #ifdef CONFIG_HUGETLB_HIGH_GRANULARITY_MAPPING bool hugetlb_hgm_enabled(struct vm_area_struct *vma); +bool hugetlb_hgm_advised(struct vm_area_struct *vma); bool hugetlb_hgm_eligible(struct vm_area_struct *vma); +int hugetlb_alloc_largest_pte(struct hugetlb_pte *hpte, struct mm_struct *mm, + struct vm_area_struct *vma, unsigned long start, + unsigned long end); #else static inline bool hugetlb_hgm_enabled(struct vm_area_struct *vma) { return false; } +static inline bool hugetlb_hgm_advised(struct vm_area_struct *vma) +{ + return false; +} static inline bool hugetlb_hgm_eligible(struct vm_area_struct *vma) { return false; } +static inline +int hugetlb_alloc_largest_pte(struct hugetlb_pte *hpte, struct mm_struct *mm, + struct vm_area_struct *vma, unsigned long start, + unsigned long end) +{ + return -EINVAL; +} #endif static inline spinlock_t *huge_pte_lock(struct hstate *h, diff --git a/mm/hugetlb.c b/mm/hugetlb.c index 1eef6968b1fa..5af6db52f34e 100644 --- a/mm/hugetlb.c +++ b/mm/hugetlb.c @@ -5936,6 +5936,13 @@ static inline vm_fault_t hugetlb_handle_userfault(struct vm_area_struct *vma, unsigned long addr, unsigned long reason) { + /* + * Don't use the hpage-aligned address if the user has explicitly + * enabled HGM. + */ + if (hugetlb_hgm_advised(vma) && reason == VM_UFFD_MINOR) + haddr = address & PAGE_MASK; + u32 hash; struct vm_fault vmf = { .vma = vma, @@ -6420,7 +6427,7 @@ vm_fault_t hugetlb_fault(struct mm_struct *mm, struct vm_area_struct *vma, * modifications for huge pages. */ int hugetlb_mcopy_atomic_pte(struct mm_struct *dst_mm, - pte_t *dst_pte, + struct hugetlb_pte *dst_hpte, struct vm_area_struct *dst_vma, unsigned long dst_addr, unsigned long src_addr, @@ -6431,13 +6438,14 @@ int hugetlb_mcopy_atomic_pte(struct mm_struct *dst_mm, bool is_continue = (mode == MCOPY_ATOMIC_CONTINUE); struct hstate *h = hstate_vma(dst_vma); struct address_space *mapping = dst_vma->vm_file->f_mapping; - pgoff_t idx = vma_hugecache_offset(h, dst_vma, dst_addr); + unsigned long haddr = dst_addr & huge_page_mask(h); + pgoff_t idx = vma_hugecache_offset(h, dst_vma, haddr); unsigned long size; int vm_shared = dst_vma->vm_flags & VM_SHARED; pte_t _dst_pte; spinlock_t *ptl; int ret = -ENOMEM; - struct page *page; + struct page *page, *subpage; int writable; bool page_in_pagecache = false; @@ -6452,12 +6460,12 @@ int hugetlb_mcopy_atomic_pte(struct mm_struct *dst_mm, * a non-missing case. Return -EEXIST. */ if (vm_shared && - hugetlbfs_pagecache_present(h, dst_vma, dst_addr)) { + hugetlbfs_pagecache_present(h, dst_vma, haddr)) { ret = -EEXIST; goto out; } - page = alloc_huge_page(dst_vma, dst_addr, 0); + page = alloc_huge_page(dst_vma, haddr, 0); if (IS_ERR(page)) { ret = -ENOMEM; goto out; @@ -6473,13 +6481,13 @@ int hugetlb_mcopy_atomic_pte(struct mm_struct *dst_mm, /* Free the allocated page which may have * consumed a reservation. */ - restore_reserve_on_error(h, dst_vma, dst_addr, page); + restore_reserve_on_error(h, dst_vma, haddr, page); put_page(page); /* Allocate a temporary page to hold the copied * contents. */ - page = alloc_huge_page_vma(h, dst_vma, dst_addr); + page = alloc_huge_page_vma(h, dst_vma, haddr); if (!page) { ret = -ENOMEM; goto out; @@ -6493,14 +6501,14 @@ int hugetlb_mcopy_atomic_pte(struct mm_struct *dst_mm, } } else { if (vm_shared && - hugetlbfs_pagecache_present(h, dst_vma, dst_addr)) { + hugetlbfs_pagecache_present(h, dst_vma, haddr)) { put_page(*pagep); ret = -EEXIST; *pagep = NULL; goto out; } - page = alloc_huge_page(dst_vma, dst_addr, 0); + page = alloc_huge_page(dst_vma, haddr, 0); if (IS_ERR(page)) { put_page(*pagep); ret = -ENOMEM; @@ -6548,7 +6556,7 @@ int hugetlb_mcopy_atomic_pte(struct mm_struct *dst_mm, page_in_pagecache = true; } - ptl = huge_pte_lock(h, dst_mm, dst_pte); + ptl = hugetlb_pte_lock(dst_hpte); ret = -EIO; if (PageHWPoison(page)) @@ -6560,7 +6568,7 @@ int hugetlb_mcopy_atomic_pte(struct mm_struct *dst_mm, * page backing it, then access the page. */ ret = -EEXIST; - if (!huge_pte_none_mostly(huge_ptep_get(dst_pte))) + if (!huge_pte_none_mostly(huge_ptep_get(dst_hpte->ptep))) goto out_release_unlock; if (page_in_pagecache) @@ -6577,7 +6585,10 @@ int hugetlb_mcopy_atomic_pte(struct mm_struct *dst_mm, else writable = dst_vma->vm_flags & VM_WRITE; - _dst_pte = make_huge_pte(dst_vma, page, writable); + subpage = hugetlb_find_subpage(h, page, dst_addr); + + _dst_pte = make_huge_pte_with_shift(dst_vma, subpage, writable, + dst_hpte->shift); /* * Always mark UFFDIO_COPY page dirty; note that this may not be * extremely important for hugetlbfs for now since swapping is not @@ -6590,12 +6601,12 @@ int hugetlb_mcopy_atomic_pte(struct mm_struct *dst_mm, if (wp_copy) _dst_pte = huge_pte_mkuffd_wp(_dst_pte); - set_huge_pte_at(dst_mm, dst_addr, dst_pte, _dst_pte); + set_huge_pte_at(dst_mm, dst_addr, dst_hpte->ptep, _dst_pte); - hugetlb_count_add(pages_per_huge_page(h), dst_mm); + hugetlb_count_add(hugetlb_pte_size(dst_hpte) / PAGE_SIZE, dst_mm); /* No need to invalidate - it was non-present before */ - update_mmu_cache(dst_vma, dst_addr, dst_pte); + update_mmu_cache(dst_vma, dst_addr, dst_hpte->ptep); spin_unlock(ptl); if (!is_continue) @@ -7780,6 +7791,18 @@ bool hugetlb_hgm_enabled(struct vm_area_struct *vma) { return vma && (vma->vm_flags & VM_HUGETLB_HGM); } +bool hugetlb_hgm_advised(struct vm_area_struct *vma) +{ + /* + * Right now, the only way for HGM to be enabled is if a user + * explicitly enables it via MADV_SPLIT, but in the future, there + * may be cases where it gets enabled automatically. + * + * Provide hugetlb_hgm_advised() now for call sites where care that the + * user explicitly enabled HGM. + */ + return hugetlb_hgm_enabled(vma); +} /* Should only be used by the for_each_hgm_shift macro. */ static unsigned int __shift_for_hstate(struct hstate *h) { @@ -7798,6 +7821,38 @@ static unsigned int __shift_for_hstate(struct hstate *h) (tmp_h) <= &hstates[hugetlb_max_hstate]; \ (tmp_h)++) +/* + * Find the HugeTLB PTE that maps as much of [start, end) as possible with a + * single page table entry. It is returned in @hpte. + */ +int hugetlb_alloc_largest_pte(struct hugetlb_pte *hpte, struct mm_struct *mm, + struct vm_area_struct *vma, unsigned long start, + unsigned long end) +{ + struct hstate *h = hstate_vma(vma), *tmp_h; + unsigned int shift; + unsigned long sz; + int ret; + + for_each_hgm_shift(h, tmp_h, shift) { + sz = 1UL << shift; + + if (!IS_ALIGNED(start, sz) || start + sz > end) + continue; + goto found; + } + return -EINVAL; +found: + ret = hugetlb_full_walk_alloc(hpte, vma, start, sz); + if (ret) + return ret; + + if (hpte->shift > shift) + return -EEXIST; + + return 0; +} + #endif /* CONFIG_HUGETLB_HIGH_GRANULARITY_MAPPING */ /* diff --git a/mm/userfaultfd.c b/mm/userfaultfd.c index 65ad172add27..2b233d31be24 100644 --- a/mm/userfaultfd.c +++ b/mm/userfaultfd.c @@ -320,14 +320,16 @@ static __always_inline ssize_t __mcopy_atomic_hugetlb(struct mm_struct *dst_mm, { int vm_shared = dst_vma->vm_flags & VM_SHARED; ssize_t err; - pte_t *dst_pte; unsigned long src_addr, dst_addr; long copied; struct page *page; - unsigned long vma_hpagesize; + unsigned long vma_hpagesize, target_pagesize; pgoff_t idx; u32 hash; struct address_space *mapping; + bool use_hgm = hugetlb_hgm_advised(dst_vma) && + mode == MCOPY_ATOMIC_CONTINUE; + struct hstate *h = hstate_vma(dst_vma); /* * There is no default zero huge page for all huge page sizes as @@ -345,12 +347,13 @@ static __always_inline ssize_t __mcopy_atomic_hugetlb(struct mm_struct *dst_mm, copied = 0; page = NULL; vma_hpagesize = vma_kernel_pagesize(dst_vma); + target_pagesize = use_hgm ? PAGE_SIZE : vma_hpagesize; /* - * Validate alignment based on huge page size + * Validate alignment based on the targeted page size. */ err = -EINVAL; - if (dst_start & (vma_hpagesize - 1) || len & (vma_hpagesize - 1)) + if (dst_start & (target_pagesize - 1) || len & (target_pagesize - 1)) goto out_unlock; retry: @@ -381,13 +384,14 @@ static __always_inline ssize_t __mcopy_atomic_hugetlb(struct mm_struct *dst_mm, } while (src_addr < src_start + len) { + struct hugetlb_pte hpte; BUG_ON(dst_addr >= dst_start + len); /* * Serialize via vma_lock and hugetlb_fault_mutex. - * vma_lock ensures the dst_pte remains valid even - * in the case of shared pmds. fault mutex prevents - * races with other faulting threads. + * vma_lock ensures the hpte.ptep remains valid even + * in the case of shared pmds and page table collapsing. + * fault mutex prevents races with other faulting threads. */ idx = linear_page_index(dst_vma, dst_addr); mapping = dst_vma->vm_file->f_mapping; @@ -395,23 +399,28 @@ static __always_inline ssize_t __mcopy_atomic_hugetlb(struct mm_struct *dst_mm, mutex_lock(&hugetlb_fault_mutex_table[hash]); hugetlb_vma_lock_read(dst_vma); - err = -ENOMEM; - dst_pte = huge_pte_alloc(dst_mm, dst_vma, dst_addr, vma_hpagesize); - if (!dst_pte) { + if (use_hgm) + err = hugetlb_alloc_largest_pte(&hpte, dst_mm, dst_vma, + dst_addr, + dst_start + len); + else + err = hugetlb_full_walk_alloc(&hpte, dst_vma, dst_addr, + vma_hpagesize); + if (err) { hugetlb_vma_unlock_read(dst_vma); mutex_unlock(&hugetlb_fault_mutex_table[hash]); goto out_unlock; } if (mode != MCOPY_ATOMIC_CONTINUE && - !huge_pte_none_mostly(huge_ptep_get(dst_pte))) { + !huge_pte_none_mostly(huge_ptep_get(hpte.ptep))) { err = -EEXIST; hugetlb_vma_unlock_read(dst_vma); mutex_unlock(&hugetlb_fault_mutex_table[hash]); goto out_unlock; } - err = hugetlb_mcopy_atomic_pte(dst_mm, dst_pte, dst_vma, + err = hugetlb_mcopy_atomic_pte(dst_mm, &hpte, dst_vma, dst_addr, src_addr, mode, &page, wp_copy); @@ -423,6 +432,7 @@ static __always_inline ssize_t __mcopy_atomic_hugetlb(struct mm_struct *dst_mm, if (unlikely(err == -ENOENT)) { mmap_read_unlock(dst_mm); BUG_ON(!page); + WARN_ON_ONCE(hpte.shift != huge_page_shift(h)); err = copy_huge_page_from_user(page, (const void __user *)src_addr, @@ -440,9 +450,9 @@ static __always_inline ssize_t __mcopy_atomic_hugetlb(struct mm_struct *dst_mm, BUG_ON(page); if (!err) { - dst_addr += vma_hpagesize; - src_addr += vma_hpagesize; - copied += vma_hpagesize; + dst_addr += hugetlb_pte_size(&hpte); + src_addr += hugetlb_pte_size(&hpte); + copied += hugetlb_pte_size(&hpte); if (fatal_signal_pending(current)) err = -EINTR;