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authorShakeel Butt <shakeelb@google.com>2021-04-29 22:56:36 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2021-04-30 11:20:38 -0700
commit0add0c77a9bd0ce7cd3b53894fb08154881402a4 (patch)
tree217aa2f31f53d5bd07ba3491e4f4048bb3fc32aa /include
parent4bbcc5a41c5449f6a67edb3fbc2dccae9c6724db (diff)
memcg: charge before adding to swapcache on swapin
Currently the kernel adds the page, allocated for swapin, to the swapcache before charging the page. This is fine but now we want a per-memcg swapcache stat which is essential for folks who wants to transparently migrate from cgroup v1's memsw to cgroup v2's memory and swap counters. In addition charging a page before exposing it to other parts of the kernel is a step in the right direction. To correctly maintain the per-memcg swapcache stat, this patch has adopted to charge the page before adding it to swapcache. One challenge in this option is the failure case of add_to_swap_cache() on which we need to undo the mem_cgroup_charge(). Specifically undoing mem_cgroup_uncharge_swap() is not simple. To resolve the issue, this patch decouples the charging for swapin pages from mem_cgroup_charge(). Two new functions are introduced, mem_cgroup_swapin_charge_page() for just charging the swapin page and mem_cgroup_swapin_uncharge_swap() for uncharging the swap slot once the page has been successfully added to the swapcache. [shakeelb@google.com: set page->private before calling swap_readpage] Link: https://lkml.kernel.org/r/20210318015959.2986837-1-shakeelb@google.com Link: https://lkml.kernel.org/r/20210305212639.775498-1-shakeelb@google.com Signed-off-by: Shakeel Butt <shakeelb@google.com> Acked-by: Roman Gushchin <guro@fb.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Acked-by: Hugh Dickins <hughd@google.com> Tested-by: Heiko Carstens <hca@linux.ibm.com> Cc: Michal Hocko <mhocko@kernel.org> Cc: Stephen Rothwell <sfr@canb.auug.org.au> Cc: Christian Borntraeger <borntraeger@de.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'include')
-rw-r--r--include/linux/memcontrol.h13
1 files changed, 13 insertions, 0 deletions
diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h
index 74910ce9a3f9..e946c96daa32 100644
--- a/include/linux/memcontrol.h
+++ b/include/linux/memcontrol.h
@@ -609,6 +609,9 @@ static inline bool mem_cgroup_below_min(struct mem_cgroup *memcg)
}
int mem_cgroup_charge(struct page *page, struct mm_struct *mm, gfp_t gfp_mask);
+int mem_cgroup_swapin_charge_page(struct page *page, struct mm_struct *mm,
+ gfp_t gfp, swp_entry_t entry);
+void mem_cgroup_swapin_uncharge_swap(swp_entry_t entry);
void mem_cgroup_uncharge(struct page *page);
void mem_cgroup_uncharge_list(struct list_head *page_list);
@@ -1112,6 +1115,16 @@ static inline int mem_cgroup_charge(struct page *page, struct mm_struct *mm,
return 0;
}
+static inline int mem_cgroup_swapin_charge_page(struct page *page,
+ struct mm_struct *mm, gfp_t gfp, swp_entry_t entry)
+{
+ return 0;
+}
+
+static inline void mem_cgroup_swapin_uncharge_swap(swp_entry_t entry)
+{
+}
+
static inline void mem_cgroup_uncharge(struct page *page)
{
}