Commit b1e1ef34 authored by Yang Shi's avatar Yang Shi Committed by Linus Torvalds
Browse files

Revert "mm/shmem: fix shmem_swapin() race with swapoff" 

Due to the change about how block layer detects congestion the
justification of commit 8fd2e0b5 ("mm: swap: check if swap backing
device is congested or not") doesn't stand anymore, so the commit could
be just reverted in order to solve the race reported by commit
2efa33fc ("mm/shmem: fix shmem_swapin() race with swapoff"), so the
fix commit could be just reverted as well.

And that fix is also kind of buggy as discussed by [1] and [2].

[1] https://lore.kernel.org/linux-mm/24187e5e-069-9f3f-cefe-39ac70783753@google.com/
[2] https://lore.kernel.org/linux-mm/e82380b9-3ad4-4a52-be50-6d45c7f2b5da@google.com/

Link: https://lkml.kernel.org/r/20210810202936.2672-2-shy828301@gmail.com


Signed-off-by: default avatarYang Shi <shy828301@gmail.com>
Suggested-by: default avatarHugh Dickins <hughd@google.com>
Acked-by: default avatarHugh Dickins <hughd@google.com>
Cc: "Huang, Ying" <ying.huang@intel.com>
Cc: Miaohe Lin <linmiaohe@huawei.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Minchan Kim <minchan@kernel.org>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 614cb275

mm/shmem.c

+1 −13
Original line number Diff line number Diff line
@@ -1696,8 +1696,7 @@ static int shmem_swapin_page(struct inode *inode, pgoff_t index, 
	struct address_space *mapping = inode->i_mapping;

	struct shmem_inode_info *info = SHMEM_I(inode);

	struct mm_struct *charge_mm = vma ? vma->vm_mm : NULL;

	struct swap_info_struct *si;

	struct page *page = NULL;

	struct page *page;

	swp_entry_t swap;

	int error;
@@ -1705,12 +1704,6 @@ static int shmem_swapin_page(struct inode *inode, pgoff_t index, 
	swap = radix_to_swp_entry(*pagep);

	*pagep = NULL;



	/* Prevent swapoff from happening to us. */

	si = get_swap_device(swap);

	if (!si) {

		error = EINVAL;

		goto failed;

	}

	/* Look it up and read it in.. */

	page = lookup_swap_cache(swap, NULL, 0);

	if (!page) {
@@ -1772,8 +1765,6 @@ static int shmem_swapin_page(struct inode *inode, pgoff_t index, 
	swap_free(swap);



	*pagep = page;

	if (si)

		put_swap_device(si);

	return 0;

failed:

	if (!shmem_confirm_swap(mapping, index, swap))
@@ -1784,9 +1775,6 @@ static int shmem_swapin_page(struct inode *inode, pgoff_t index, 
		put_page(page);

	}



	if (si)

		put_swap_device(si);



	return error;

}