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mm: rename __mlock_vma_pages_range() to populate_vma_page_range()

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__mlock_vma_pages_range() doesn't necessarily mlock pages.  It depends on
vma flags.  The same codepath is used for MAP_POPULATE.

Let's rename __mlock_vma_pages_range() to populate_vma_page_range().

This patch also drops mlock_vma_pages_range() references from
documentation.  It has gone in cea10a19b7 ("mm: directly use
__mlock_vma_pages_range() in find_extend_vma()").

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Acked-by: David Rientjes <rientjes@google.com>
Cc: Michel Lespinasse <walken@google.com>
Cc: Rik van Riel <riel@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Kirill A. Shutemov 2015-04-14 15:44:39 -07:00 • committed by Linus Torvalds
parent 84d33df279
commit fc05f56621
4 changed files with 16 additions and 26 deletions
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24
Documentation/vm/unevictable-lru.txt
View file

@ -317,7 +317,7 @@ If the VMA passes some filtering as described in "Filtering Special Vmas"
below, mlock_fixup() will attempt to merge the VMA with its neighbors or split
off a subset of the VMA if the range does not cover the entire VMA. Once the
VMA has been merged or split or neither, mlock_fixup() will call
__mlock_vma_pages_range() to fault in the pages via get_user_pages() and to
populate_vma_page_range() to fault in the pages via get_user_pages() and to
mark the pages as mlocked via mlock_vma_page().
Note that the VMA being mlocked might be mapped with PROT_NONE. In this case,
@ -327,7 +327,7 @@ fault path or in vmscan.
Also note that a page returned by get_user_pages() could be truncated or
migrated out from under us, while we're trying to mlock it. To detect this,
__mlock_vma_pages_range() checks page_mapping() after acquiring the page lock.
populate_vma_page_range() checks page_mapping() after acquiring the page lock.
If the page is still associated with its mapping, we'll go ahead and call
mlock_vma_page(). If the mapping is gone, we just unlock the page and move on.
In the worst case, this will result in a page mapped in a VM_LOCKED VMA
@ -392,7 +392,7 @@ ignored for munlock.
If the VMA is VM_LOCKED, mlock_fixup() again attempts to merge or split off the
specified range. The range is then munlocked via the function
__mlock_vma_pages_range() - the same function used to mlock a VMA range -
populate_vma_page_range() - the same function used to mlock a VMA range -
passing a flag to indicate that munlock() is being performed.
Because the VMA access protections could have been changed to PROT_NONE after
@ -402,7 +402,7 @@ get_user_pages() was enhanced to accept a flag to ignore the permissions when
fetching the pages - all of which should be resident as a result of previous
mlocking.
For munlock(), __mlock_vma_pages_range() unlocks individual pages by calling
For munlock(), populate_vma_page_range() unlocks individual pages by calling
munlock_vma_page(). munlock_vma_page() unconditionally clears the PG_mlocked
flag using TestClearPageMlocked(). As with mlock_vma_page(),
munlock_vma_page() use the Test*PageMlocked() function to handle the case where
@ -463,21 +463,11 @@ populate the page table.
To mlock a range of memory under the unevictable/mlock infrastructure, the
mmap() handler and task address space expansion functions call
mlock_vma_pages_range() specifying the vma and the address range to mlock.
mlock_vma_pages_range() filters VMAs like mlock_fixup(), as described above in
"Filtering Special VMAs". It will clear the VM_LOCKED flag, which will have
already been set by the caller, in filtered VMAs. Thus these VMA's need not be
visited for munlock when the region is unmapped.
populate_vma_page_range() specifying the vma and the address range to mlock.
For "normal" VMAs, mlock_vma_pages_range() calls __mlock_vma_pages_range() to
fault/allocate the pages and mlock them. Again, like mlock_fixup(),
mlock_vma_pages_range() downgrades the mmap semaphore to read mode before
attempting to fault/allocate and mlock the pages and "upgrades" the semaphore
back to write mode before returning.
The callers of mlock_vma_pages_range() will have already added the memory range
The callers of populate_vma_page_range() will have already added the memory range
to be mlocked to the task's "locked_vm". To account for filtered VMAs,
mlock_vma_pages_range() returns the number of pages NOT mlocked. All of the
populate_vma_page_range() returns the number of pages NOT mlocked. All of the
callers then subtract a non-negative return value from the task's locked_vm. A
negative return value represent an error - for example, from get_user_pages()
attempting to fault in a VMA with PROT_NONE access. In this case, we leave the