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[115.124.30.132]) by mx.google.com with ESMTPS id h130-v6si7941113pfe.119.2018.08.09.16.36.30 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Thu, 09 Aug 2018 16:36:30 -0700 (PDT) From: Yang Shi Subject: [RFC v7 PATCH 1/4] mm: refactor do_munmap() to extract the common part Date: Fri, 10 Aug 2018 07:36:00 +0800 Message-Id: <1533857763-43527-2-git-send-email-yang.shi@linux.alibaba.com> In-Reply-To: <1533857763-43527-1-git-send-email-yang.shi@linux.alibaba.com> References: <1533857763-43527-1-git-send-email-yang.shi@linux.alibaba.com> Sender: owner-linux-mm@kvack.org List-ID: To: mhocko@kernel.org, willy@infradead.org, ldufour@linux.vnet.ibm.com, kirill@shutemov.name, vbabka@suse.cz, akpm@linux-foundation.org, peterz@infradead.org, mingo@redhat.com, acme@kernel.org, alexander.shishkin@linux.intel.com, jolsa@redhat.com, namhyung@kernel.org Cc: yang.shi@linux.alibaba.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org Introduces three new helper functions: * addr_ok() * munmap_lookup_vma() * munlock_vmas() They will be used by do_munmap() and the new do_munmap with zapping large mapping early in the later patch. There is no functional change, just code refactor. Reviewed-by: Laurent Dufour Signed-off-by: Yang Shi --- mm/mmap.c | 100 ++++++++++++++++++++++++++++++++++++++++++++------------------ 1 file changed, 71 insertions(+), 29 deletions(-) diff --git a/mm/mmap.c b/mm/mmap.c index 17bbf4d..2a6898b 100644 --- a/mm/mmap.c +++ b/mm/mmap.c @@ -2681,35 +2681,40 @@ int split_vma(struct mm_struct *mm, struct vm_area_struct *vma, return __split_vma(mm, vma, addr, new_below); } -/* Munmap is split into 2 main parts -- this part which finds - * what needs doing, and the areas themselves, which do the - * work. This now handles partial unmappings. - * Jeremy Fitzhardinge - */ -int do_munmap(struct mm_struct *mm, unsigned long start, size_t len, - struct list_head *uf) +static inline bool addr_ok(unsigned long start, size_t len) { - unsigned long end; - struct vm_area_struct *vma, *prev, *last; - if ((offset_in_page(start)) || start > TASK_SIZE || len > TASK_SIZE-start) - return -EINVAL; + return false; - len = PAGE_ALIGN(len); - if (len == 0) - return -EINVAL; + if (PAGE_ALIGN(len) == 0) + return false; + + return true; +} + +/* + * munmap_lookup_vma: find the first overlap vma and split overlap vmas. + * @mm: mm_struct + * @start: start address + * @end: end address + * + * returns the pointer to vma, NULL or err ptr when spilt_vma returns error. + */ +static struct vm_area_struct *munmap_lookup_vma(struct mm_struct *mm, + unsigned long start, unsigned long end) +{ + struct vm_area_struct *vma, *prev, *last; /* Find the first overlapping VMA */ vma = find_vma(mm, start); if (!vma) - return 0; - prev = vma->vm_prev; - /* we have start < vma->vm_end */ + return NULL; + /* we have start < vma->vm_end */ /* if it doesn't overlap, we have nothing.. */ - end = start + len; if (vma->vm_start >= end) - return 0; + return NULL; + prev = vma->vm_prev; /* * If we need to split any vma, do it now to save pain later. @@ -2727,11 +2732,11 @@ int do_munmap(struct mm_struct *mm, unsigned long start, size_t len, * its limit temporarily, to help free resources as expected. */ if (end < vma->vm_end && mm->map_count >= sysctl_max_map_count) - return -ENOMEM; + return ERR_PTR(-ENOMEM); error = __split_vma(mm, vma, start, 0); if (error) - return error; + return ERR_PTR(error); prev = vma; } @@ -2740,10 +2745,53 @@ int do_munmap(struct mm_struct *mm, unsigned long start, size_t len, if (last && end > last->vm_start) { int error = __split_vma(mm, last, end, 1); if (error) - return error; + return ERR_PTR(error); } vma = prev ? prev->vm_next : mm->mmap; + return vma; +} + +static inline void munlock_vmas(struct vm_area_struct *vma, + unsigned long end) +{ + struct mm_struct *mm = vma->vm_mm; + + while (vma && vma->vm_start < end) { + if (vma->vm_flags & VM_LOCKED) { + mm->locked_vm -= vma_pages(vma); + munlock_vma_pages_all(vma); + } + vma = vma->vm_next; + } +} + +/* Munmap is split into 2 main parts -- this part which finds + * what needs doing, and the areas themselves, which do the + * work. This now handles partial unmappings. + * Jeremy Fitzhardinge + */ +int do_munmap(struct mm_struct *mm, unsigned long start, size_t len, + struct list_head *uf) +{ + unsigned long end; + struct vm_area_struct *vma, *prev; + + if (!addr_ok(start, len)) + return -EINVAL; + + len = PAGE_ALIGN(len); + + end = start + len; + + vma = munmap_lookup_vma(mm, start, end); + if (!vma) + return 0; + if (IS_ERR(vma)) + return PTR_ERR(vma); + + prev = vma->vm_prev; + if (unlikely(uf)) { /* * If userfaultfd_unmap_prep returns an error the vmas @@ -2764,13 +2812,7 @@ int do_munmap(struct mm_struct *mm, unsigned long start, size_t len, */ if (mm->locked_vm) { struct vm_area_struct *tmp = vma; - while (tmp && tmp->vm_start < end) { - if (tmp->vm_flags & VM_LOCKED) { - mm->locked_vm -= vma_pages(tmp); - munlock_vma_pages_all(tmp); - } - tmp = tmp->vm_next; - } + munlock_vmas(tmp, end); } /* -- 1.8.3.1