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Date:   Fri, 6 Nov 2020 20:55:36 +0000
From:   Matthew Wilcox <willy@infradead.org>
To:     Rong Chen <rong.a.chen@intel.com>
Cc:     Linus Torvalds <torvalds@linux-foundation.org>,
        Andrew Morton <akpm@linux-foundation.org>,
        Johannes Weiner <hannes@cmpxchg.org>,
        Alexey Dobriyan <adobriyan@gmail.com>,
        Chris Wilson <chris@chris-wilson.co.uk>,
        Huang Ying <ying.huang@intel.com>,
        Hugh Dickins <hughd@google.com>,
        Jani Nikula <jani.nikula@linux.intel.com>,
        Matthew Auld <matthew.auld@intel.com>,
        William Kucharski <william.kucharski@oracle.com>,
        Qian Cai <cai@redhat.com>, LKML <linux-kernel@vger.kernel.org>,
        lkp@lists.01.org, lkp@intel.com, feng.tang@intel.com,
        zhengjun.xing@intel.com
Subject: Re: [mm] e6e88712e4: stress-ng.tmpfs.ops_per_sec -69.7% regression
Message-ID: <20201106205536.GS17076@casper.infradead.org>
References: <20201030071715.GV31092@shao2-debian>
 <20201030131711.GJ27442@casper.infradead.org>
 <dc3864d6-f474-02b8-fdf2-ca138afe3735@intel.com>
 <20201030145835.GL27442@casper.infradead.org>
 <d57f327c-a22e-1fb0-26fe-68b4964e75dc@intel.com>
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On Mon, Nov 02, 2020 at 01:21:39PM +0800, Rong Chen wrote:
> we compared the tmpfs.ops_per_sec: (363 / 103.02) between this commit and
> parent commit.

Thanks!  I see about a 50% hit on my system, and this patch restores the
performance.  Can you verify this works for you?

diff --git a/mm/madvise.c b/mm/madvise.c
index 9b065d412e5f..e602333f8c0d 100644
--- a/mm/madvise.c
+++ b/mm/madvise.c
@@ -225,7 +225,7 @@ static void force_shm_swapin_readahead(struct vm_area_struct *vma,
 		struct address_space *mapping)
 {
 	XA_STATE(xas, &mapping->i_pages, linear_page_index(vma, start));
-	pgoff_t end_index = end / PAGE_SIZE;
+	pgoff_t end_index = linear_page_index(vma, end + PAGE_SIZE - 1);
 	struct page *page;
 
 	rcu_read_lock();