+ memcg-charge-before-adding-to-swapcache-on-swapin-fix.patch added to -mm tree

+ memcg-charge-before-adding-to-swapcache-on-swapin-fix.patch added to -mm tree

[akpm]

The patch titled
     Subject: memcg: set page->private before calling swap_readpage
has been added to the -mm tree.  Its filename is
     memcg-charge-before-adding-to-swapcache-on-swapin-fix.patch

This patch should soon appear at
    https://ozlabs.org/~akpm/mmots/broken-out/memcg-charge-before-adding-to-swapcache-on-swapin-fix.patch
and later at
    https://ozlabs.org/~akpm/mmotm/broken-out/memcg-charge-before-adding-to-swapcache-on-swapin-fix.patch

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------------------------------------------------------
From: Shakeel Butt <shakeelb@google.com>
Subject: memcg: set page->private before calling swap_readpage

The function swap_readpage() (and other functions it call) extracts swap
entry from page->private.  However for SWP_SYNCHRONOUS_IO, the kernel
skips the swapcache and thus we need to manually set the page->private
with the swap entry before calling swap_readpage().

Link: https://lkml.kernel.org/r/20210318015959.2986837-1-shakeelb@google.com
Signed-off-by: Shakeel Butt <shakeelb@google.com>
Reported-by: Heiko Carstens <hca@linux.ibm.com>
Cc: Roman Gushchin <guro@fb.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Hugh Dickins <hughd@google.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>
---

 mm/memory.c |    4 ++++
 1 file changed, 4 insertions(+)

--- a/mm/memory.c~memcg-charge-before-adding-to-swapcache-on-swapin-fix
+++ a/mm/memory.c
@@ -3324,7 +3324,11 @@ vm_fault_t do_swap_page(struct vm_fault
 					workingset_refault(page, shadow);
 
 				lru_cache_add(page);
+
+				/* To provide entry to swap_readpage() */
+				set_page_private(page, entry.val);
 				swap_readpage(page, true);
+				set_page_private(page, 0);
 			}
 		} else {
 			page = swapin_readahead(entry, GFP_HIGHUSER_MOVABLE,
_

Patches currently in -mm which might be from shakeelb@google.com are

memcg-cleanup-root-memcg-checks.patch
memcg-enable-memcg-oom-kill-for-__gfp_nofail.patch
memcg-charge-before-adding-to-swapcache-on-swapin.patch
memcg-charge-before-adding-to-swapcache-on-swapin-fix.patch