From mboxrd@z Thu Jan 1 00:00:00 1970 From: Andrew Morton Subject: [patch 38/67] mm: pagewalk: add 'depth' parameter to pte_hole Date: Mon, 03 Feb 2020 17:36:03 -0800 Message-ID: <20200204013603.Q2V-TR4Dr%akpm@linux-foundation.org> References: <20200203173311.6269a8be06a05e5a4aa08a93@linux-foundation.org> Reply-To: linux-kernel@vger.kernel.org Return-path: Received: from mail.kernel.org ([198.145.29.99]:36142 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726369AbgBDBgG (ORCPT ); Mon, 3 Feb 2020 20:36:06 -0500 In-Reply-To: <20200203173311.6269a8be06a05e5a4aa08a93@linux-foundation.org> Sender: mm-commits-owner@vger.kernel.org List-Id: mm-commits@vger.kernel.org To: akpm@linux-foundation.org, alex@ghiti.fr, aou@eecs.berkeley.edu, ard.biesheuvel@linaro.org, arnd@arndb.de, benh@kernel.crashing.org, borntraeger@de.ibm.com, bp@alien8.de, catalin.marinas@arm.com, dave.hansen@linux.intel.com, davem@davemloft.net, gor@linux.ibm.com, heiko.carstens@de.ibm.com, hpa@zytor.com, james.morse@arm.com, jglisse@redhat.com, jhogan@kernel.org, kan.liang@linux.intel.com, linux-mm@kvack.org, linux@armlinux.org.uk, luto@kernel.org, mark.rutland@arm.com, mingo@redhat.com, mm-commits@vger.kernel.org, mpe@ellerman.id.au, paul.burton@mips.com, paul.walmsley@sifive.com, paulus@samba.org, peterz@infradead.org, ralf@linux-mips.org, steven.price@arm.com, tglx@linutronix.de, torvalds@linux-foundation.org, vgupta@synopsys.com, will@kernel.org, zong.li@sifive.com From: Steven Price Subject: mm: pagewalk: add 'depth' parameter to pte_hole The pte_hole() callback is called at multiple levels of the page tables. Code dumping the kernel page tables needs to know what at what depth the missing entry is. Add this is an extra parameter to pte_hole(). When the depth isn't know (e.g. processing a vma) then -1 is passed. The depth that is reported is the actual level where the entry is missing (ignoring any folding that is in place), i.e. any levels where PTRS_PER_P?D is set to 1 are ignored. Note that depth starts at 0 for a PGD so that PUD/PMD/PTE retain their natural numbers as levels 2/3/4. Link: http://lkml.kernel.org/r/20191218162402.45610-16-steven.price@arm.com Signed-off-by: Steven Price Tested-by: Zong Li Cc: Albert Ou Cc: Alexandre Ghiti Cc: Andy Lutomirski Cc: Ard Biesheuvel Cc: Arnd Bergmann Cc: Benjamin Herrenschmidt Cc: Borislav Petkov Cc: Catalin Marinas Cc: Christian Borntraeger Cc: Dave Hansen Cc: David S. Miller Cc: Heiko Carstens Cc: "H. Peter Anvin" Cc: Ingo Molnar Cc: James Hogan Cc: James Morse Cc: Jerome Glisse Cc: "Liang, Kan" Cc: Mark Rutland Cc: Michael Ellerman Cc: Paul Burton Cc: Paul Mackerras Cc: Paul Walmsley Cc: Peter Zijlstra Cc: Ralf Baechle Cc: Russell King Cc: Thomas Gleixner Cc: Vasily Gorbik Cc: Vineet Gupta Cc: Will Deacon Signed-off-by: Andrew Morton --- fs/proc/task_mmu.c | 4 ++-- include/linux/pagewalk.h | 7 +++++-- mm/hmm.c | 8 ++++---- mm/migrate.c | 5 +++-- mm/mincore.c | 1 + mm/pagewalk.c | 31 +++++++++++++++++++++++++------ 6 files changed, 40 insertions(+), 16 deletions(-) --- a/fs/proc/task_mmu.c~mm-pagewalk-add-depth-parameter-to-pte_hole +++ a/fs/proc/task_mmu.c @@ -505,7 +505,7 @@ static void smaps_account(struct mem_siz #ifdef CONFIG_SHMEM static int smaps_pte_hole(unsigned long addr, unsigned long end, - struct mm_walk *walk) + __always_unused int depth, struct mm_walk *walk) { struct mem_size_stats *mss = walk->private; @@ -1282,7 +1282,7 @@ static int add_to_pagemap(unsigned long } static int pagemap_pte_hole(unsigned long start, unsigned long end, - struct mm_walk *walk) + __always_unused int depth, struct mm_walk *walk) { struct pagemapread *pm = walk->private; unsigned long addr = start; --- a/include/linux/pagewalk.h~mm-pagewalk-add-depth-parameter-to-pte_hole +++ a/include/linux/pagewalk.h @@ -17,7 +17,10 @@ struct mm_walk; * split_huge_page() instead of handling it explicitly. * @pte_entry: if set, called for each non-empty PTE (lowest-level) * entry - * @pte_hole: if set, called for each hole at all levels + * @pte_hole: if set, called for each hole at all levels, + * depth is -1 if not known, 0:PGD, 1:P4D, 2:PUD, 3:PMD + * 4:PTE. Any folded depths (where PTRS_PER_P?D is equal + * to 1) are skipped. * @hugetlb_entry: if set, called for each hugetlb entry * @test_walk: caller specific callback function to determine whether * we walk over the current vma or not. Returning 0 means @@ -43,7 +46,7 @@ struct mm_walk_ops { int (*pte_entry)(pte_t *pte, unsigned long addr, unsigned long next, struct mm_walk *walk); int (*pte_hole)(unsigned long addr, unsigned long next, - struct mm_walk *walk); + int depth, struct mm_walk *walk); int (*hugetlb_entry)(pte_t *pte, unsigned long hmask, unsigned long addr, unsigned long next, struct mm_walk *walk); --- a/mm/hmm.c~mm-pagewalk-add-depth-parameter-to-pte_hole +++ a/mm/hmm.c @@ -186,7 +186,7 @@ static void hmm_range_need_fault(const s } static int hmm_vma_walk_hole(unsigned long addr, unsigned long end, - struct mm_walk *walk) + __always_unused int depth, struct mm_walk *walk) { struct hmm_vma_walk *hmm_vma_walk = walk->private; struct hmm_range *range = hmm_vma_walk->range; @@ -380,7 +380,7 @@ static int hmm_vma_walk_pmd(pmd_t *pmdp, again: pmd = READ_ONCE(*pmdp); if (pmd_none(pmd)) - return hmm_vma_walk_hole(start, end, walk); + return hmm_vma_walk_hole(start, end, -1, walk); if (thp_migration_supported() && is_pmd_migration_entry(pmd)) { bool fault, write_fault; @@ -487,7 +487,7 @@ static int hmm_vma_walk_pud(pud_t *pudp, pud = READ_ONCE(*pudp); if (pud_none(pud)) { - ret = hmm_vma_walk_hole(start, end, walk); + ret = hmm_vma_walk_hole(start, end, -1, walk); goto out_unlock; } @@ -497,7 +497,7 @@ static int hmm_vma_walk_pud(pud_t *pudp, bool fault, write_fault; if (!pud_present(pud)) { - ret = hmm_vma_walk_hole(start, end, walk); + ret = hmm_vma_walk_hole(start, end, -1, walk); goto out_unlock; } --- a/mm/migrate.c~mm-pagewalk-add-depth-parameter-to-pte_hole +++ a/mm/migrate.c @@ -2151,6 +2151,7 @@ out_unlock: #ifdef CONFIG_DEVICE_PRIVATE static int migrate_vma_collect_hole(unsigned long start, unsigned long end, + __always_unused int depth, struct mm_walk *walk) { struct migrate_vma *migrate = walk->private; @@ -2195,7 +2196,7 @@ static int migrate_vma_collect_pmd(pmd_t again: if (pmd_none(*pmdp)) - return migrate_vma_collect_hole(start, end, walk); + return migrate_vma_collect_hole(start, end, -1, walk); if (pmd_trans_huge(*pmdp)) { struct page *page; @@ -2228,7 +2229,7 @@ again: return migrate_vma_collect_skip(start, end, walk); if (pmd_none(*pmdp)) - return migrate_vma_collect_hole(start, end, + return migrate_vma_collect_hole(start, end, -1, walk); } } --- a/mm/mincore.c~mm-pagewalk-add-depth-parameter-to-pte_hole +++ a/mm/mincore.c @@ -112,6 +112,7 @@ static int __mincore_unmapped_range(unsi } static int mincore_unmapped_range(unsigned long addr, unsigned long end, + __always_unused int depth, struct mm_walk *walk) { walk->private += __mincore_unmapped_range(addr, end, --- a/mm/pagewalk.c~mm-pagewalk-add-depth-parameter-to-pte_hole +++ a/mm/pagewalk.c @@ -4,6 +4,22 @@ #include #include +/* + * We want to know the real level where a entry is located ignoring any + * folding of levels which may be happening. For example if p4d is folded then + * a missing entry found at level 1 (p4d) is actually at level 0 (pgd). + */ +static int real_depth(int depth) +{ + if (depth == 3 && PTRS_PER_PMD == 1) + depth = 2; + if (depth == 2 && PTRS_PER_PUD == 1) + depth = 1; + if (depth == 1 && PTRS_PER_P4D == 1) + depth = 0; + return depth; +} + static int walk_pte_range_inner(pte_t *pte, unsigned long addr, unsigned long end, struct mm_walk *walk) { @@ -49,6 +65,7 @@ static int walk_pmd_range(pud_t *pud, un unsigned long next; const struct mm_walk_ops *ops = walk->ops; int err = 0; + int depth = real_depth(3); pmd = pmd_offset(pud, addr); do { @@ -56,7 +73,7 @@ again: next = pmd_addr_end(addr, end); if (pmd_none(*pmd) || (!walk->vma && !walk->no_vma)) { if (ops->pte_hole) - err = ops->pte_hole(addr, next, walk); + err = ops->pte_hole(addr, next, depth, walk); if (err) break; continue; @@ -106,6 +123,7 @@ static int walk_pud_range(p4d_t *p4d, un unsigned long next; const struct mm_walk_ops *ops = walk->ops; int err = 0; + int depth = real_depth(2); pud = pud_offset(p4d, addr); do { @@ -113,7 +131,7 @@ static int walk_pud_range(p4d_t *p4d, un next = pud_addr_end(addr, end); if (pud_none(*pud) || (!walk->vma && !walk->no_vma)) { if (ops->pte_hole) - err = ops->pte_hole(addr, next, walk); + err = ops->pte_hole(addr, next, depth, walk); if (err) break; continue; @@ -154,13 +172,14 @@ static int walk_p4d_range(pgd_t *pgd, un unsigned long next; const struct mm_walk_ops *ops = walk->ops; int err = 0; + int depth = real_depth(1); p4d = p4d_offset(pgd, addr); do { next = p4d_addr_end(addr, end); if (p4d_none_or_clear_bad(p4d)) { if (ops->pte_hole) - err = ops->pte_hole(addr, next, walk); + err = ops->pte_hole(addr, next, depth, walk); if (err) break; continue; @@ -192,7 +211,7 @@ static int walk_pgd_range(unsigned long next = pgd_addr_end(addr, end); if (pgd_none_or_clear_bad(pgd)) { if (ops->pte_hole) - err = ops->pte_hole(addr, next, walk); + err = ops->pte_hole(addr, next, 0, walk); if (err) break; continue; @@ -239,7 +258,7 @@ static int walk_hugetlb_range(unsigned l if (pte) err = ops->hugetlb_entry(pte, hmask, addr, next, walk); else if (ops->pte_hole) - err = ops->pte_hole(addr, next, walk); + err = ops->pte_hole(addr, next, -1, walk); if (err) break; @@ -283,7 +302,7 @@ static int walk_page_test(unsigned long if (vma->vm_flags & VM_PFNMAP) { int err = 1; if (ops->pte_hole) - err = ops->pte_hole(start, end, walk); + err = ops->pte_hole(start, end, -1, walk); return err ? err : 1; } return 0; _