[PATCH v12 69/69] mm/mmap.c: pass in mapping to __vma_link_file()

Liam Howlett
2022-07-20T02:24:56Z

__vma_link_file() resolves the mapping from the file, if there is one.
Pass through the mapping and check the vm_file externally since most
places already have the required information and check of vm_file.

Link: https://lkml.kernel.org/r/20220504011345.662299-54-Liam.Howlett@oracle.com
Link: https://lkml.kernel.org/r/20220621204632.3370049-70-Liam.Howlett@oracle.com
Signed-off-by: Liam R. Howlett <Liam.Howlett@oracle.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: David Howells <dhowells@redhat.com>
Cc: "Matthew Wilcox (Oracle)" <willy@infradead.org>
Cc: SeongJae Park <sj@kernel.org>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Will Deacon <will@kernel.org>
Cc: Davidlohr Bueso <dave@stgolabs.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---
mm/mmap.c | 33 +++++++++++++++------------------
1 file changed, 15 insertions(+), 18 deletions(-)

diff --git a/mm/mmap.c b/mm/mmap.c
index a9ebe25c5b09..37990e66feeb 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -246,6 +246,7 @@ SYSCALL_DEFINE1(brk, unsigned long, brk)
if (brk < min_brk)
goto out;

+
/*
* Check against rlimit here. If this check is done later after the test
* of oldbrk with newbrk then it can escape the test and let the data
@@ -322,7 +323,6 @@ SYSCALL_DEFINE1(brk, unsigned long, brk)
if (populate)
mm_populate(oldbrk, newbrk - oldbrk);
return brk;
-
out:
mmap_write_unlock(mm);
return origbrk;
@@ -454,21 +454,15 @@ static unsigned long count_vma_pages_range(struct mm_struct *mm,
return nr_pages;
}

-static void __vma_link_file(struct vm_area_struct *vma)
+static void __vma_link_file(struct vm_area_struct *vma,
+ struct address_space *mapping)
{
- struct file *file;
-
- file = vma->vm_file;
- if (file) {
- struct address_space *mapping = file->f_mapping;
-
- if (vma->vm_flags & VM_SHARED)
- mapping_allow_writable(mapping);
+ if (vma->vm_flags & VM_SHARED)
+ mapping_allow_writable(mapping);

- flush_dcache_mmap_lock(mapping);
- vma_interval_tree_insert(vma, &mapping->i_mmap);
- flush_dcache_mmap_unlock(mapping);
- }
+ flush_dcache_mmap_lock(mapping);
+ vma_interval_tree_insert(vma, &mapping->i_mmap);
+ flush_dcache_mmap_unlock(mapping);
}

/*
@@ -535,10 +529,11 @@ static int vma_link(struct mm_struct *mm, struct vm_area_struct *vma)
}

vma_mas_store(vma, &mas);
- __vma_link_file(vma);

- if (mapping)
+ if (mapping) {
+ __vma_link_file(vma, mapping);
i_mmap_unlock_write(mapping);
+ }

mm->map_count++;
validate_mm(mm);
@@ -777,14 +772,14 @@ int __vma_adjust(struct vm_area_struct *vma, unsigned long start,
uprobe_munmap(next, next->vm_start, next->vm_end);

i_mmap_lock_write(mapping);
- if (insert) {
+ if (insert && insert->vm_file) {
/*
* Put into interval tree now, so instantiated pages
* are visible to arm/parisc __flush_dcache_page
* throughout; but we cannot insert into address
* space until vma start or end is updated.
*/
- __vma_link_file(insert);
+ __vma_link_file(insert, insert->vm_file->f_mapping);
}
}

@@ -2982,6 +2977,7 @@ static int do_brk_flags(struct ma_state *mas, struct vm_area_struct *vma,
struct mm_struct *mm = current->mm;

validate_mm_mt(mm);
+
/*
* Check against address space limits by the changed size
* Note: This happens *after* clearing old mappings in some code paths.
@@ -3039,6 +3035,7 @@ static int do_brk_flags(struct ma_state *mas, struct vm_area_struct *vma,
goto mas_store_fail;

mm->map_count++;
+
out:
perf_event_mmap(vma);
mm->total_vm += len >> PAGE_SHIFT;
--
2.35.1