Revert "swap: fix do_swap_page() race with swapoff"

This reverts commit 8e4af3917bfc5e82f8010417c12b755ef256fa5e 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>

diff --git a/include/linux/swap.h b/include/linux/swap.h
index dfabf46..fbc6805 100644 (file)
--- a/include/linux/swap.h
+++ b/include/linux/swap.h
@@ -503,15 +503,6 @@ static inline struct swap_info_struct *swp_swap_info(swp_entry_t entry)
        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

diff --git a/mm/memory.c b/mm/memory.c
index 0a905e0..eb31b3e 100644 (file)
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -3302,7 +3302,6 @@ vm_fault_t do_swap_page(struct vm_fault *vmf)
 {
        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;
@@ -3330,16 +3329,14 @@ vm_fault_t do_swap_page(struct vm_fault *vmf)
                goto out;
        }
 
-       /* Prevent swapoff from happening to us. */
-       si = get_swap_device(entry);
-       if (unlikely(!si))
-               goto out;
 
        delayacct_set_flag(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 */
@@ -3510,8 +3507,6 @@ vm_fault_t do_swap_page(struct vm_fault *vmf)
 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);
@@ -3523,8 +3518,6 @@ out_release:
                unlock_page(swapcache);
                put_page(swapcache);
        }
-       if (si)
-               put_swap_device(si);
        return ret;
 }