The patch titled
Subject: mm/z3fold.c: lock z3fold page before __SetPageMovable()
has been added to the -mm tree. Its filename is
mm-z3foldc-lock-z3fold-page-before-__setpagemovable.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/mm-z3foldc-lock-z3fold-page-before-__setpagemovable.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/mm-z3foldc-lock-z3fold-page-before-__setpagemovable.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: lock z3fold page before __SetPageMovable()
__SetPageMovable() expects its page to be locked, but z3fold.c doesn't
lock the page. This triggers the VM_BUG_ON_PAGE(!PageLocked(page), page)
in __SetPageMovable().
Following zsmalloc.c's example we call trylock_page() and unlock_page().
Also make z3fold_page_migrate() assert that newpage is passed in locked,
as per the documentation.
Link: http://lkml.kernel.org/r/20190702005122.41036-1-henryburns@xxxxxxxxxx
Signed-off-by: Henry Burns <henryburns@xxxxxxxxxx>
Suggested-by: Vitaly Wool <vitalywool@xxxxxxxxx>
Acked-by: Vitaly Wool <vitalywool@xxxxxxxxx>
Acked-by: David Rientjes <rientjes@xxxxxxxxxx>
Cc: Shakeel Butt <shakeelb@xxxxxxxxxx>
Cc: Vitaly Vul <vitaly.vul@xxxxxxxx>
Cc: Mike Rapoport <rppt@xxxxxxxxxxxxxxxxxx>
Cc: Xidong Wang <wangxidong_97@xxxxxxx>
Cc: Jonathan Adams <jwadams@xxxxxxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/z3fold.c | 6 +++++-
1 file changed, 5 insertions(+), 1 deletion(-)
--- a/mm/z3fold.c~mm-z3foldc-lock-z3fold-page-before-__setpagemovable
+++ a/mm/z3fold.c
@@ -919,7 +919,10 @@ retry:
set_bit(PAGE_HEADLESS, &page->private);
goto headless;
}
- __SetPageMovable(page, pool->inode->i_mapping);
+ if (!WARN_ON(!trylock_page(page))) {
+ __SetPageMovable(page, pool->inode->i_mapping);
+ unlock_page(page);
+ }
z3fold_page_lock(zhdr);
found:
@@ -1326,6 +1329,7 @@ static int z3fold_page_migrate(struct ad
VM_BUG_ON_PAGE(!PageMovable(page), page);
VM_BUG_ON_PAGE(!PageIsolated(page), page);
+ VM_BUG_ON_PAGE(!PageLocked(newpage), newpage);
zhdr = page_address(page);
pool = zhdr_to_pool(zhdr);
_
Patches currently in -mm which might be from henryburns@xxxxxxxxxx are
mm-z3fold-fix-z3fold_buddy_slots-use-after-free.patch
mm-z3foldc-lock-z3fold-page-before-__setpagemovable.patch
