The patch titled
Subject: mm/z3fold.c: reinitialize zhdr structs after migration
has been added to the -mm tree. Its filename is
mm-z3foldc-reinitialize-zhdr-structs-after-migration.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/mm-z3foldc-reinitialize-zhdr-structs-after-migration.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/mm-z3foldc-reinitialize-zhdr-structs-after-migration.patch
Before you just go and hit "reply", please:
a) Consider who else should be cc'ed
b) Prefer to cc a suitable mailing list as well
c) Ideally: find the original patch on the mailing list and do a
reply-to-all to that, adding suitable additional cc's
*** Remember to use Documentation/process/submit-checklist.rst when testing your code ***
The -mm tree is included into linux-next and is updated
there every 3-4 working days
------------------------------------------------------
From: Henry Burns <henryburns@xxxxxxxxxx>
Subject: mm/z3fold.c: reinitialize zhdr structs after migration
z3fold_page_migration() calls memcpy(new_zhdr, zhdr, PAGE_SIZE). However,
zhdr contains fields that can't be directly coppied over (ex: list_head, a
circular linked list). We only need to initialize the linked lists in
new_zhdr, as z3fold_isolate_page() already ensures that these lists are
empty
Additionally it is possible that zhdr->work has been placed in a
workqueue. In this case we shouldn't migrate the page, as zhdr->work
references zhdr as opposed to new_zhdr.
Link: http://lkml.kernel.org/r/20190716000520.230595-1-henryburns@xxxxxxxxxx
Fixes: 1f862989b04ade61d3 ("mm/z3fold.c: support page migration")
Signed-off-by: Henry Burns <henryburns@xxxxxxxxxx>
Cc: Vitaly Vul <vitaly.vul@xxxxxxxx>
Cc: Vitaly Wool <vitalywool@xxxxxxxxx>
Cc: Shakeel Butt <shakeelb@xxxxxxxxxx>
Cc: Jonathan Adams <jwadams@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/z3fold.c | 10 ++++++++++
1 file changed, 10 insertions(+)
--- a/mm/z3fold.c~mm-z3foldc-reinitialize-zhdr-structs-after-migration
+++ a/mm/z3fold.c
@@ -1357,12 +1357,22 @@ static int z3fold_page_migrate(struct ad
z3fold_page_unlock(zhdr);
return -EBUSY;
}
+ if (work_pending(&zhdr->work)) {
+ z3fold_page_unlock(zhdr);
+ return -EAGAIN;
+ }
new_zhdr = page_address(newpage);
memcpy(new_zhdr, zhdr, PAGE_SIZE);
newpage->private = page->private;
page->private = 0;
z3fold_page_unlock(zhdr);
spin_lock_init(&new_zhdr->page_lock);
+ INIT_WORK(&new_zhdr->work, compact_page_work);
+ /*
+ * z3fold_page_isolate() ensures that new_zhdr->buddy is empty,
+ * so we only have to reinitialize it.
+ */
+ INIT_LIST_HEAD(&new_zhdr->buddy);
new_mapping = page_mapping(page);
__ClearPageMovable(page);
ClearPagePrivate(page);
_
Patches currently in -mm which might be from henryburns@xxxxxxxxxx are
mm-z3foldc-allow-__gfp_highmem-in-z3fold_alloc.patch
mm-z3foldc-remove-z3fold_migration-trylock.patch
mm-z3foldc-reinitialize-zhdr-structs-after-migration.patch
