From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: From: Josef Bacik To: kernel-team@fb.com, linux-kernel@vger.kernel.org, hannes@cmpxchg.org, tj@kernel.org, linux-fsdevel@vger.kernel.org, akpm@linux-foundation.org, riel@redhat.com, linux-mm@kvack.org, linux-btrfs@vger.kernel.org Cc: Johannes Weiner Subject: [PATCH 4/9] mm: drop mmap_sem for swap read IO submission Date: Wed, 26 Sep 2018 17:08:51 -0400 Message-Id: <20180926210856.7895-5-josef@toxicpanda.com> In-Reply-To: <20180926210856.7895-1-josef@toxicpanda.com> References: <20180926210856.7895-1-josef@toxicpanda.com> Sender: owner-linux-mm@kvack.org List-ID: From: Johannes Weiner We don't need to hold the mmap_sem while we're doing the IO, simply drop it and retry appropriately. Signed-off-by: Johannes Weiner Signed-off-by: Josef Bacik --- mm/page_io.c | 14 ++++++++++++++ 1 file changed, 14 insertions(+) diff --git a/mm/page_io.c b/mm/page_io.c index aafd19ec1db4..bf21b56a964e 100644 --- a/mm/page_io.c +++ b/mm/page_io.c @@ -365,6 +365,20 @@ int swap_readpage(struct page *page, bool synchronous) goto out; } + /* + * XXX: + * + * Propagate mm->mmap_sem into this function. Then: + * + * get_file(sis->swap_file) + * up_read(mm->mmap_sem) + * submit io request + * fput + * + * After mmap_sem is dropped, sis is no longer valid. Go + * through swap_file->blah->bdev. + */ + if (sis->flags & SWP_FILE) { struct file *swap_file = sis->swap_file; struct address_space *mapping = swap_file->f_mapping; -- 2.14.3