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mm/rmap: extend rmap_walk_xxx() to cope with different cases

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There are a lot of common parts in traversing functions, but there are
also a little of uncommon parts in it.  By assigning proper function
pointer on each rmap_walker_control, we can handle these difference
correctly.

Following are differences we should handle.

1. difference of lock function in anon mapping case
2. nonlinear handling in file mapping case
3. prechecked condition:
	checking memcg in page_referenced(),
	checking VM_SHARE in page_mkclean()
	checking temporary vma in try_to_unmap()
4. exit condition:
	checking page_mapped() in try_to_unmap()

So, in this patch, I introduce 4 function pointers to handle above
differences.

Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Hugh Dickins <hughd@google.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Hillf Danton <dhillf@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Joonsoo Kim 2014-01-21 15:49:49 -08:00 committed by Linus Torvalds
parent 051ac83adf
commit 0dd1c7bbce
3 changed files with 51 additions and 8 deletions
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15
include/linux/rmap.h
View File

@ -235,10 +235,25 @@ struct anon_vma *page_lock_anon_vma_read(struct page *page);
void page_unlock_anon_vma_read(struct anon_vma *anon_vma);
int page_mapped_in_vma(struct page *page, struct vm_area_struct *vma);
/*
* rmap_walk_control: To control rmap traversing for specific needs
*
* arg: passed to rmap_one() and invalid_vma()
* rmap_one: executed on each vma where page is mapped
* done: for checking traversing termination condition
* file_nonlinear: for handling file nonlinear mapping
* anon_lock: for getting anon_lock by optimized way rather than default
* invalid_vma: for skipping uninterested vma
*/
struct rmap_walk_control {
void *arg;
int (*rmap_one)(struct page *page, struct vm_area_struct *vma,
unsigned long addr, void *arg);
int (*done)(struct page *page);
int (*file_nonlinear)(struct page *, struct address_space *,
struct vm_area_struct *vma);
struct anon_vma *(*anon_lock)(struct page *page);
bool (*invalid_vma)(struct vm_area_struct *vma, void *arg);
};
/*

7
mm/ksm.c
View File

@ -2032,12 +2032,19 @@ again:
if ((rmap_item->mm == vma->vm_mm) == search_new_forks)
continue;
if (rwc->invalid_vma && rwc->invalid_vma(vma, rwc->arg))
continue;
ret = rwc->rmap_one(page, vma,
rmap_item->address, rwc->arg);
if (ret != SWAP_AGAIN) {
anon_vma_unlock_read(anon_vma);
goto out;
}
if (rwc->done && rwc->done(page)) {
anon_vma_unlock_read(anon_vma);
goto out;
}
}
anon_vma_unlock_read(anon_vma);
}

37
mm/rmap.c
View File

@ -1684,10 +1684,14 @@ void __put_anon_vma(struct anon_vma *anon_vma)
}
#ifdef CONFIG_MIGRATION
static struct anon_vma *rmap_walk_anon_lock(struct page *page)
static struct anon_vma *rmap_walk_anon_lock(struct page *page,
struct rmap_walk_control *rwc)
{
struct anon_vma *anon_vma;
if (rwc->anon_lock)
return rwc->anon_lock(page);
/*
* Note: remove_migration_ptes() cannot use page_lock_anon_vma_read()
* because that depends on page_mapped(); but not all its usages
@ -1713,16 +1717,22 @@ static int rmap_walk_anon(struct page *page, struct rmap_walk_control *rwc)
struct anon_vma_chain *avc;
int ret = SWAP_AGAIN;
anon_vma = rmap_walk_anon_lock(page);
anon_vma = rmap_walk_anon_lock(page, rwc);
if (!anon_vma)
return ret;
anon_vma_interval_tree_foreach(avc, &anon_vma->rb_root, pgoff, pgoff) {
struct vm_area_struct *vma = avc->vma;
unsigned long address = vma_address(page, vma);
if (rwc->invalid_vma && rwc->invalid_vma(vma, rwc->arg))
continue;
ret = rwc->rmap_one(page, vma, address, rwc->arg);
if (ret != SWAP_AGAIN)
break;
if (rwc->done && rwc->done(page))
break;
}
anon_vma_unlock_read(anon_vma);
return ret;
@ -1740,15 +1750,26 @@ static int rmap_walk_file(struct page *page, struct rmap_walk_control *rwc)
mutex_lock(&mapping->i_mmap_mutex);
vma_interval_tree_foreach(vma, &mapping->i_mmap, pgoff, pgoff) {
unsigned long address = vma_address(page, vma);
if (rwc->invalid_vma && rwc->invalid_vma(vma, rwc->arg))
continue;
ret = rwc->rmap_one(page, vma, address, rwc->arg);
if (ret != SWAP_AGAIN)
break;
goto done;
if (rwc->done && rwc->done(page))
goto done;
}
/*
* No nonlinear handling: being always shared, nonlinear vmas
* never contain migration ptes. Decide what to do about this
* limitation to linear when we need rmap_walk() on nonlinear.
*/
if (!rwc->file_nonlinear)
goto done;
if (list_empty(&mapping->i_mmap_nonlinear))
goto done;
ret = rwc->file_nonlinear(page, mapping, vma);
done:
mutex_unlock(&mapping->i_mmap_mutex);
return ret;
}