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    Subject[PATCH 5.13 103/156] Revert "swap: fix do_swap_page() race with swapoff"
    Date
    From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

    This reverts commit c3b39134bbd088b7dce5e5f342ccd6bb9142fd18 which is
    commit 2799e77529c2a25492a4395db93996e3dacd762d upstream.

    It should not have been added to the stable trees, sorry about that.

    Link: https://lore.kernel.org/r/YPVgaY6uw59Fqg5x@casper.infradead.org
    Reported-by: From: Matthew Wilcox <willy@infradead.org>
    Cc: Miaohe Lin <linmiaohe@huawei.com>
    Cc: Ying Huang <ying.huang@intel.com>
    Cc: Alex Shi <alexs@kernel.org>
    Cc: David Hildenbrand <david@redhat.com>
    Cc: Dennis Zhou <dennis@kernel.org>
    Cc: Hugh Dickins <hughd@google.com>
    Cc: Johannes Weiner <hannes@cmpxchg.org>
    Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
    Cc: Matthew Wilcox <willy@infradead.org>
    Cc: Michal Hocko <mhocko@suse.com>
    Cc: Minchan Kim <minchan@kernel.org>
    Cc: Tim Chen <tim.c.chen@linux.intel.com>
    Cc: Wei Yang <richard.weiyang@gmail.com>
    Cc: Yang Shi <shy828301@gmail.com>
    Cc: Yu Zhao <yuzhao@google.com>
    Cc: Andrew Morton <akpm@linux-foundation.org>
    Cc: Linus Torvalds <torvalds@linux-foundation.org>
    Cc: Sasha Levin <sashal@kernel.org>
    Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
    ---
    include/linux/swap.h | 9 ---------
    mm/memory.c | 11 ++---------
    2 files changed, 2 insertions(+), 18 deletions(-)

    --- a/include/linux/swap.h
    +++ b/include/linux/swap.h
    @@ -526,15 +526,6 @@ static inline struct swap_info_struct *s
    return NULL;
    }

    -static inline struct swap_info_struct *get_swap_device(swp_entry_t entry)
    -{
    - return NULL;
    -}
    -
    -static inline void put_swap_device(struct swap_info_struct *si)
    -{
    -}
    -
    #define swap_address_space(entry) (NULL)
    #define get_nr_swap_pages() 0L
    #define total_swap_pages 0L
    --- a/mm/memory.c
    +++ b/mm/memory.c
    @@ -3353,7 +3353,6 @@ vm_fault_t do_swap_page(struct vm_fault
    {
    struct vm_area_struct *vma = vmf->vma;
    struct page *page = NULL, *swapcache;
    - struct swap_info_struct *si = NULL;
    swp_entry_t entry;
    pte_t pte;
    int locked;
    @@ -3381,16 +3380,14 @@ vm_fault_t do_swap_page(struct vm_fault
    goto out;
    }

    - /* Prevent swapoff from happening to us. */
    - si = get_swap_device(entry);
    - if (unlikely(!si))
    - goto out;

    delayacct_set_flag(current, DELAYACCT_PF_SWAPIN);
    page = lookup_swap_cache(entry, vma, vmf->address);
    swapcache = page;

    if (!page) {
    + struct swap_info_struct *si = swp_swap_info(entry);
    +
    if (data_race(si->flags & SWP_SYNCHRONOUS_IO) &&
    __swap_count(entry) == 1) {
    /* skip swapcache */
    @@ -3559,8 +3556,6 @@ vm_fault_t do_swap_page(struct vm_fault
    unlock:
    pte_unmap_unlock(vmf->pte, vmf->ptl);
    out:
    - if (si)
    - put_swap_device(si);
    return ret;
    out_nomap:
    pte_unmap_unlock(vmf->pte, vmf->ptl);
    @@ -3572,8 +3567,6 @@ out_release:
    unlock_page(swapcache);
    put_page(swapcache);
    }
    - if (si)
    - put_swap_device(si);
    return ret;
    }


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