kernel/mm/z3fold.c, branch linux-6.6.y

mm/z3fold: remove obsolete comment for struct z3fold_pool

2023-08-21T20:37:51Z

Since commit e774a7bc7f0a ("mm: zswap: remove page reclaim logic from z3fold"), zpool and zpool_ops have been removed, so also remove the corresponding comments. Link: https://lkml.kernel.org/r/20230814221142.486548-1-xiujianfeng@huaweicloud.com Signed-off-by: Xiu Jianfeng Reviewed-by: Miaohe Lin Cc: Vitaly Wool Signed-off-by: Andrew Morton

mm/z3fold: use helper function put_z3fold_locked() and put_z3fold_locked_list()

2023-08-21T20:37:38Z

This code is already duplicated six times, use helper function put_z3fold_locked() to release z3fold page instead of open code it to help improve code readability a bit. And add put_z3fold_locked_list() helper function to be consistent with it. No functional change involved. Link: https://lkml.kernel.org/r/20230803113824.886413-1-ruanjinjie@huawei.com Signed-off-by: Ruan Jinjie Reviewed-by: Miaohe Lin Cc: Vitaly Wool Signed-off-by: Andrew Morton

mm: zswap: remove shrink from zpool interface

2023-06-19T23:19:27Z

Now that all three zswap backends have removed their shrink code, it is no longer necessary for the zpool interface to include shrink/writeback endpoints. Link: https://lkml.kernel.org/r/20230612093815.133504-6-cerasuolodomenico@gmail.com Signed-off-by: Domenico Cerasuolo Reviewed-by: Yosry Ahmed Acked-by: Nhat Pham Acked-by: Johannes Weiner Reviewed-by: Sergey Senozhatsky Cc: Dan Streetman Cc: Minchan Kim Cc: Seth Jennings Cc: Vitaly Wool Signed-off-by: Andrew Morton

mm: zswap: remove page reclaim logic from z3fold

2023-06-19T23:19:26Z

Switch z3fold to the new generic zswap LRU and remove its custom implementation. Link: https://lkml.kernel.org/r/20230612093815.133504-4-cerasuolodomenico@gmail.com Signed-off-by: Domenico Cerasuolo Acked-by: Johannes Weiner Cc: Dan Streetman Cc: Minchan Kim Cc: Nhat Pham Cc: Sergey Senozhatsky Cc: Seth Jennings Cc: Vitaly Wool Cc: Yosry Ahmed Signed-off-by: Andrew Morton

mm: remove PageMovable export

2023-01-19T01:12:57Z

The only in-kernel users that need PageMovable() to be exported are z3fold and zsmalloc and they are only using it for dubious debugging functionality. So remove those usages and the export so that no driver code accidentally thinks that they are allowed to use this symbol. Link: https://lkml.kernel.org/r/20230106135900.3763622-1-gregkh@linuxfoundation.org Signed-off-by: Greg Kroah-Hartman Reviewed-by: Sergey Senozhatsky Reviewed-by: Miaohe Lin Reviewed-by: David Hildenbrand Reviewed-by: Christoph Hellwig Acked-by: Minchan Kim Cc: Vitaly Wool Signed-off-by: Andrew Morton

zpool: clean out dead code

2022-12-12T02:12:10Z

There is a lot of provision for flexibility that isn't actually needed or used. Zswap (the only zpool user) always passes zpool_ops with an .evict method set. The backends who reclaim only do so for zswap, so they can also directly call zpool_ops without indirection or checks. Finally, there is no need to check the retries parameters and bail with -EINVAL in the reclaim function, when that's called just a few lines below with a hard-coded 8. There is no need to duplicate the evictable and sleep_mapped attrs from the driver in zpool_ops. Link: https://lkml.kernel.org/r/20221128191616.1261026-3-nphamcs@gmail.com Reviewed-by: Sergey Senozhatsky Signed-off-by: Johannes Weiner Signed-off-by: Nhat Pham Cc: Dan Streetman Cc: Minchan Kim Cc: Nitin Gupta Cc: Seth Jennings Cc: Vitaly Wool Signed-off-by: Andrew Morton

mm: Convert all PageMovable users to movable_operations

2022-08-02T16:34:03Z

These drivers are rather uncomfortably hammered into the address_space_operations hole. They aren't filesystems and don't behave like filesystems. They just need their own movable_operations structure, which we can point to directly from page->mapping. Signed-off-by: Matthew Wilcox (Oracle)

mm/z3fold: fix z3fold_page_migrate races with z3fold_map

2022-05-27T16:33:44Z

Think about the below scenario: CPU1 CPU2 z3fold_page_migrate z3fold_map z3fold_page_trylock ... z3fold_page_unlock /* slots still points to old zhdr*/ get_z3fold_header get slots from handle get old zhdr from slots z3fold_page_trylock return *old* zhdr encode_handle(new_zhdr, FIRST|LAST|MIDDLE) put_page(page) /* zhdr is freed! */ but zhdr is still used by caller! z3fold_map can map freed z3fold page and lead to use-after-free bug. To fix it, we add PAGE_MIGRATED to indicate z3fold page is migrated and soon to be released. So get_z3fold_header won't return such page. Link: https://lkml.kernel.org/r/20220429064051.61552-10-linmiaohe@huawei.com Fixes: 1f862989b04a ("mm/z3fold.c: support page migration") Signed-off-by: Miaohe Lin Reviewed-by: Vitaly Wool Signed-off-by: Andrew Morton

mm/z3fold: fix z3fold_reclaim_page races with z3fold_free

2022-05-27T16:33:44Z

Think about the below scenario: CPU1 CPU2 z3fold_reclaim_page z3fold_free spin_lock(&pool->lock) get_z3fold_header -- hold page_lock kref_get_unless_zero kref_put--zhdr->refcount can be 1 now !z3fold_page_trylock kref_put -- zhdr->refcount is 0 now release_z3fold_page WARN_ON(!list_empty(&zhdr->buddy)); -- we're on buddy now! spin_lock(&pool->lock); -- deadlock here! z3fold_reclaim_page might race with z3fold_free and will lead to pool lock deadlock and zhdr buddy non-empty warning. To fix this, defer getting the refcount until page_lock is held just like what __z3fold_alloc does. Note this has the side effect that we won't break the reclaim if we meet a soon to be released z3fold page now. Link: https://lkml.kernel.org/r/20220429064051.61552-9-linmiaohe@huawei.com Fixes: dcf5aedb24f8 ("z3fold: stricter locking and more careful reclaim") Signed-off-by: Miaohe Lin Reviewed-by: Vitaly Wool Signed-off-by: Andrew Morton

mm/z3fold: always clear PAGE_CLAIMED under z3fold page lock

2022-05-27T16:33:44Z

Think about the below race window: CPU1 CPU2 z3fold_reclaim_page z3fold_free test_and_set_bit PAGE_CLAIMED failed to reclaim page z3fold_page_lock(zhdr); add back to the lru list; z3fold_page_unlock(zhdr); get_z3fold_header page_claimed=test_and_set_bit PAGE_CLAIMED clear_bit(PAGE_CLAIMED, &page->private); if (!page_claimed) /* it's false true */ free_handle is not called free_handle won't be called in this case. So z3fold_buddy_slots will leak. Fix it by always clear PAGE_CLAIMED under z3fold page lock. Link: https://lkml.kernel.org/r/20220429064051.61552-8-linmiaohe@huawei.com Signed-off-by: Miaohe Lin Reviewed-by: Vitaly Wool Signed-off-by: Andrew Morton