From: Yang Shi <yang.shi@xxxxxxxxxxxxxxxxx> Subject: mm: shmem: use proper gfp flags for shmem_writepage() The shmem_writepage() uses GFP_ATOMIC to allocate swap cache. GFP_ATOMIC used to mean __GFP_HIGH, but now it means __GFP_HIGH | __GFP_ATOMIC | __GFP_KSWAPD_RECLAIM. However, shmem_writepage() should write out to swap only in response to memory pressure, so __GFP_KSWAPD_RECLAIM looks useless since the caller may be kswapd itself or in direct reclaim already. In addition, XArray node allocations from PF_MEMALLOC contexts could completely exhaust the page allocator, __GFP_NOMEMALLOC stops emergency reserves from being allocated. Here just copy the gfp flags used by add_to_swap(). Hugh: "a cleanup to make the two calls look the same when they don't need to be different (whereas the call from __read_swap_cache_async() rightly uses a lower priority gfp)". Link: http://lkml.kernel.org/r/1572991351-86061-1-git-send-email-yang.shi@xxxxxxxxxxxxxxxxx Signed-off-by: Yang Shi <yang.shi@xxxxxxxxxxxxxxxxx> Acked-by: Hugh Dickins <hughd@xxxxxxxxxx> Cc: Michal Hocko <mhocko@xxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- mm/shmem.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) --- a/mm/shmem.c~mm-shmem-use-proper-gfp-flags-for-shmem_writepage +++ a/mm/shmem.c @@ -1369,7 +1369,8 @@ static int shmem_writepage(struct page * if (list_empty(&info->swaplist)) list_add(&info->swaplist, &shmem_swaplist); - if (add_to_swap_cache(page, swap, GFP_ATOMIC) == 0) { + if (add_to_swap_cache(page, swap, + __GFP_HIGH | __GFP_NOMEMALLOC | __GFP_NOWARN) == 0) { spin_lock_irq(&info->lock); shmem_recalc_inode(inode); info->swapped++; _
