From: Shaohua Li <shli@fb.com>
To: Johannes Weiner <hannes@cmpxchg.org>
Cc: <linux-mm@kvack.org>, <linux-kernel@vger.kernel.org>,
<Kernel-team@fb.com>, <mhocko@suse.com>, <minchan@kernel.org>,
<hughd@google.com>, <riel@redhat.com>,
<mgorman@techsingularity.net>, <akpm@linux-foundation.org>
Subject: Re: [PATCH V4 4/6] mm: reclaim MADV_FREE pages
Date: Thu, 23 Feb 2017 09:19:01 -0800 [thread overview]
Message-ID: <20170223171901.GA20444@shli-mbp.local> (raw)
In-Reply-To: <20170223161342.GC4031@cmpxchg.org>
On Thu, Feb 23, 2017 at 11:13:42AM -0500, Johannes Weiner wrote:
> On Wed, Feb 22, 2017 at 10:50:42AM -0800, Shaohua Li wrote:
> > @@ -1424,6 +1424,12 @@ static int try_to_unmap_one(struct page *page, struct vm_area_struct *vma,
> > dec_mm_counter(mm, MM_ANONPAGES);
> > rp->lazyfreed++;
> > goto discard;
> > + } else if (!PageSwapBacked(page)) {
> > + /* dirty MADV_FREE page */
> > + set_pte_at(mm, address, pvmw.pte, pteval);
> > + ret = SWAP_DIRTY;
> > + page_vma_mapped_walk_done(&pvmw);
> > + break;
> > }
> >
> > if (swap_duplicate(entry) < 0) {
> > @@ -1525,8 +1531,8 @@ int try_to_unmap(struct page *page, enum ttu_flags flags)
> >
> > if (ret != SWAP_MLOCK && !page_mapcount(page)) {
> > ret = SWAP_SUCCESS;
> > - if (rp.lazyfreed && !PageDirty(page))
> > - ret = SWAP_LZFREE;
> > + if (rp.lazyfreed && PageDirty(page))
> > + ret = SWAP_DIRTY;
>
> Can this actually happen? If the page is dirty, ret should already be
> SWAP_DIRTY, right? How would a dirty page get fully unmapped?
>
> It seems to me rp.lazyfreed can be removed entirely now that we don't
> have to identify the lazyfree case anymore. The failure case is much
> easier to identify - all it takes is a single pte to be dirty.
ok, I get mixed up. Yes, this couldn't happen any more since we changed the
behavior of try_to_unmap_one. Will delete this in next post.
Thanks,
Shaohua
next prev parent reply other threads:[~2017-02-23 17:20 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-02-22 18:50 [PATCH V4 0/6] mm: fix some MADV_FREE issues Shaohua Li
2017-02-22 18:50 ` [PATCH V4 1/6] mm: delete unnecessary TTU_* flags Shaohua Li
2017-02-23 15:35 ` Johannes Weiner
2017-02-24 1:25 ` Minchan Kim
2017-02-24 3:29 ` Hillf Danton
2017-02-22 18:50 ` [PATCH V4 2/6] mm: don't assume anonymous pages have SwapBacked flag Shaohua Li
2017-02-22 18:50 ` [PATCH V4 3/6] mm: move MADV_FREE pages into LRU_INACTIVE_FILE list Shaohua Li
2017-02-23 15:58 ` Johannes Weiner
2017-02-23 16:26 ` Shaohua Li
2017-02-23 18:22 ` Johannes Weiner
2017-02-23 19:04 ` Shaohua Li
2017-02-24 1:49 ` Minchan Kim
2017-02-24 6:15 ` Shaohua Li
2017-02-24 23:37 ` Minchan Kim
2017-02-22 18:50 ` [PATCH V4 4/6] mm: reclaim MADV_FREE pages Shaohua Li
2017-02-23 16:13 ` Johannes Weiner
2017-02-23 17:19 ` Shaohua Li [this message]
2017-02-24 2:12 ` Minchan Kim
2017-02-24 6:14 ` Shaohua Li
2017-02-24 15:36 ` Johannes Weiner
2017-02-24 23:26 ` Minchan Kim
2017-02-22 18:50 ` [PATCH V4 5/6] mm: enable MADV_FREE for swapless system Shaohua Li
2017-02-22 18:50 ` [PATCH V4 6/6] proc: show MADV_FREE pages info in smaps Shaohua Li
2017-02-23 16:16 ` Johannes Weiner
2017-02-24 2:13 ` Minchan Kim
2017-02-24 17:08 ` Dave Hansen
2017-02-24 21:47 ` Shaohua Li
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