Re: [PATCH] memcg: set page->private before calling swap_readpage
From: Michal Hocko <hidden>
Date: 2021-03-18 14:02:26
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linux-mm, lkml
On Wed 17-03-21 18:59:59, Shakeel Butt wrote:
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().
One thing that is not really clear to me is whether/why this is only needed with your patch. Can you expand a bit on that please? Maybe I am just missing something obvious but I just do not see any connection.
quoted hunk ↗ jump to hunk
Signed-off-by: Shakeel Butt <redacted> Reported-by: Heiko Carstens <redacted> --- Andrew, please squash this into "memcg: charge before adding to swapcache on swapin" patch. mm/memory.c | 4 ++++ 1 file changed, 4 insertions(+)diff --git a/mm/memory.c b/mm/memory.c index aefd158ae1ea..b6f3410b5902 100644 --- a/mm/memory.c +++ b/mm/memory.c@@ -3324,7 +3324,11 @@ vm_fault_t do_swap_page(struct vm_fault *vmf) 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,-- 2.31.0.rc2.261.g7f71774620-goog
-- Michal Hocko SUSE Labs