Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756011Ab2FFKyb (ORCPT ); Wed, 6 Jun 2012 06:54:31 -0400 Received: from mail-ob0-f174.google.com ([209.85.214.174]:45499 "EHLO mail-ob0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754492Ab2FFKy2 (ORCPT ); Wed, 6 Jun 2012 06:54:28 -0400 From: Sasha Levin To: konrad.wilk@oracle.com, dan.magenheimer@oracle.com Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, Sasha Levin Subject: [PATCH 05/11] mm: frontswap: split frontswap_shrink further to eliminate locking games Date: Wed, 6 Jun 2012 12:55:09 +0200 Message-Id: <1338980115-2394-5-git-send-email-levinsasha928@gmail.com> X-Mailer: git-send-email 1.7.8.6 In-Reply-To: <1338980115-2394-1-git-send-email-levinsasha928@gmail.com> References: <1338980115-2394-1-git-send-email-levinsasha928@gmail.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2476 Lines: 79 Split frontswap_shrink to eliminate the locking issues in the original code. Signed-off-by: Sasha Levin --- mm/frontswap.c | 36 +++++++++++++++++++++--------------- 1 files changed, 21 insertions(+), 15 deletions(-) diff --git a/mm/frontswap.c b/mm/frontswap.c index a9b76cb..618ef91 100644 --- a/mm/frontswap.c +++ b/mm/frontswap.c @@ -244,6 +244,24 @@ static int __frontswap_unuse_pages(unsigned long total, unsigned long *unused, return ret; } +static int __frontswap_shrink(unsigned long target_pages, + unsigned long *pages_to_unuse, + int *type) +{ + unsigned long total_pages = 0, total_pages_to_unuse; + + lockdep_assert_held(&swap_lock); + + total_pages = __frontswap_curr_pages(); + if (total_pages <= target_pages) { + /* Nothing to do */ + *pages_to_unuse = 0; + return 0; + } + total_pages_to_unuse = total_pages - target_pages; + return __frontswap_unuse_pages(total_pages_to_unuse, pages_to_unuse, type); +} + /* * Frontswap, like a true swap device, may unnecessarily retain pages * under certain circumstances; "shrink" frontswap is essentially a @@ -254,10 +272,8 @@ static int __frontswap_unuse_pages(unsigned long total, unsigned long *unused, */ void frontswap_shrink(unsigned long target_pages) { - unsigned long total_pages = 0, total_pages_to_unuse; unsigned long pages_to_unuse = 0; int type, ret; - bool locked = false; /* * we don't want to hold swap_lock while doing a very @@ -265,20 +281,10 @@ void frontswap_shrink(unsigned long target_pages) * so restart scan from swap_list.head each time */ spin_lock(&swap_lock); - locked = true; - total_pages = __frontswap_curr_pages(); - if (total_pages <= target_pages) - goto out; - total_pages_to_unuse = total_pages - target_pages; - ret = __frontswap_unuse_pages(total_pages_to_unuse, &pages_to_unuse, &type); - if (ret < 0) - goto out; - locked = false; + ret = __frontswap_shrink(target_pages, &pages_to_unuse, &type); spin_unlock(&swap_lock); - try_to_unuse(type, true, pages_to_unuse); -out: - if (locked) - spin_unlock(&swap_lock); + if (ret == 0 && pages_to_unuse) + try_to_unuse(type, true, pages_to_unuse); return; } EXPORT_SYMBOL(frontswap_shrink); -- 1.7.8.6 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/