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authorJohannes Weiner <hannes@cmpxchg.org>2020-06-04 01:01:41 +0200
committerLinus Torvalds <torvalds@linux-foundation.org>2020-06-04 05:09:47 +0200
commit3fea5a499d57dec46043fcdb08e38eac1767bb0d (patch)
treeba8bc1eb5a8ff5d0fe20d07a94069f22125671fb /mm/filemap.c
parentmm: memcontrol: move out cgroup swaprate throttling (diff)
downloadlinux-3fea5a499d57dec46043fcdb08e38eac1767bb0d.tar.xz
linux-3fea5a499d57dec46043fcdb08e38eac1767bb0d.zip
mm: memcontrol: convert page cache to a new mem_cgroup_charge() API
The try/commit/cancel protocol that memcg uses dates back to when pages used to be uncharged upon removal from the page cache, and thus couldn't be committed before the insertion had succeeded. Nowadays, pages are uncharged when they are physically freed; it doesn't matter whether the insertion was successful or not. For the page cache, the transaction dance has become unnecessary. Introduce a mem_cgroup_charge() function that simply charges a newly allocated page to a cgroup and sets up page->mem_cgroup in one single step. If the insertion fails, the caller doesn't have to do anything but free/put the page. Then switch the page cache over to this new API. Subsequent patches will also convert anon pages, but it needs a bit more prep work. Right now, memcg depends on page->mapping being already set up at the time of charging, so that it can maintain its own MEMCG_CACHE and MEMCG_RSS counters. For anon, page->mapping is set under the same pte lock under which the page is publishd, so a single charge point that can block doesn't work there just yet. The following prep patches will replace the private memcg counters with the generic vmstat counters, thus removing the page->mapping dependency, then complete the transition to the new single-point charge API and delete the old transactional scheme. v2: leave shmem swapcache when charging fails to avoid double IO (Joonsoo) v3: rebase on preceeding shmem simplification patch Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Alex Shi <alex.shi@linux.alibaba.com> Cc: Hugh Dickins <hughd@google.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: "Kirill A. Shutemov" <kirill@shutemov.name> Cc: Michal Hocko <mhocko@suse.com> Cc: Roman Gushchin <guro@fb.com> Cc: Shakeel Butt <shakeelb@google.com> Cc: Balbir Singh <bsingharora@gmail.com> Link: http://lkml.kernel.org/r/20200508183105.225460-6-hannes@cmpxchg.org Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm/filemap.c')
-rw-r--r--mm/filemap.c24
1 files changed, 10 insertions, 14 deletions
diff --git a/mm/filemap.c b/mm/filemap.c
index f268cfffbc6e..38e6a37336a6 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -832,7 +832,6 @@ static int __add_to_page_cache_locked(struct page *page,
{
XA_STATE(xas, &mapping->i_pages, offset);
int huge = PageHuge(page);
- struct mem_cgroup *memcg;
int error;
void *old;
@@ -840,17 +839,16 @@ static int __add_to_page_cache_locked(struct page *page,
VM_BUG_ON_PAGE(PageSwapBacked(page), page);
mapping_set_update(&xas, mapping);
- if (!huge) {
- error = mem_cgroup_try_charge(page, current->mm,
- gfp_mask, &memcg);
- if (error)
- return error;
- }
-
get_page(page);
page->mapping = mapping;
page->index = offset;
+ if (!huge) {
+ error = mem_cgroup_charge(page, current->mm, gfp_mask, false);
+ if (error)
+ goto error;
+ }
+
do {
xas_lock_irq(&xas);
old = xas_load(&xas);
@@ -874,20 +872,18 @@ unlock:
xas_unlock_irq(&xas);
} while (xas_nomem(&xas, gfp_mask & GFP_RECLAIM_MASK));
- if (xas_error(&xas))
+ if (xas_error(&xas)) {
+ error = xas_error(&xas);
goto error;
+ }
- if (!huge)
- mem_cgroup_commit_charge(page, memcg, false);
trace_mm_filemap_add_to_page_cache(page);
return 0;
error:
page->mapping = NULL;
/* Leave page->index set: truncation relies upon it */
- if (!huge)
- mem_cgroup_cancel_charge(page, memcg);
put_page(page);
- return xas_error(&xas);
+ return error;
}
ALLOW_ERROR_INJECTION(__add_to_page_cache_locked, ERRNO);