From: "Kirill A. Shutemov" <kirill@shutemov.name>
To: Song Liu <songliubraving@fb.com>
Cc: "linux-mm@kvack.org" <linux-mm@kvack.org>,
"linux-fsdevel@vger.kernel.org" <linux-fsdevel@vger.kernel.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"matthew.wilcox@oracle.com" <matthew.wilcox@oracle.com>,
"kirill.shutemov@linux.intel.com"
<kirill.shutemov@linux.intel.com>,
Kernel Team <Kernel-team@fb.com>,
"william.kucharski@oracle.com" <william.kucharski@oracle.com>,
"akpm@linux-foundation.org" <akpm@linux-foundation.org>,
"hdanton@sina.com" <hdanton@sina.com>
Subject: Re: [PATCH v7 5/6] mm,thp: add read-only THP support for (non-shmem) FS
Date: Mon, 24 Jun 2019 18:15:28 +0300 [thread overview]
Message-ID: <20190624151528.fnz3hvlnyvea3ytn@box> (raw)
In-Reply-To: <5BE23F34-B611-496B-9277-A09C9CC784B1@fb.com>
On Mon, Jun 24, 2019 at 03:04:21PM +0000, Song Liu wrote:
>
>
> > On Jun 24, 2019, at 7:54 AM, Kirill A. Shutemov <kirill@shutemov.name> wrote:
> >
> > On Mon, Jun 24, 2019 at 02:42:13PM +0000, Song Liu wrote:
> >>
> >>
> >>> On Jun 24, 2019, at 7:27 AM, Kirill A. Shutemov <kirill@shutemov.name> wrote:
> >>>
> >>> On Mon, Jun 24, 2019 at 02:01:05PM +0000, Song Liu wrote:
> >>>>>> @@ -1392,6 +1403,23 @@ static void collapse_file(struct mm_struct *mm,
> >>>>>> result = SCAN_FAIL;
> >>>>>> goto xa_unlocked;
> >>>>>> }
> >>>>>> + } else if (!page || xa_is_value(page)) {
> >>>>>> + xas_unlock_irq(&xas);
> >>>>>> + page_cache_sync_readahead(mapping, &file->f_ra, file,
> >>>>>> + index, PAGE_SIZE);
> >>>>>> + lru_add_drain();
> >>>>>
> >>>>> Why?
> >>>>
> >>>> isolate_lru_page() is likely to fail if we don't drain the pagevecs.
> >>>
> >>> Please add a comment.
> >>
> >> Will do.
> >>
> >>>
> >>>>>> + page = find_lock_page(mapping, index);
> >>>>>> + if (unlikely(page == NULL)) {
> >>>>>> + result = SCAN_FAIL;
> >>>>>> + goto xa_unlocked;
> >>>>>> + }
> >>>>>> + } else if (!PageUptodate(page)) {
> >>>>>
> >>>>> Maybe we should try wait_on_page_locked() here before give up?
> >>>>
> >>>> Are you referring to the "if (!PageUptodate(page))" case?
> >>>
> >>> Yes.
> >>
> >> I think this case happens when another thread is reading the page in.
> >> I could not think of a way to trigger this condition for testing.
> >>
> >> On the other hand, with current logic, we will retry the page on the
> >> next scan, so I guess this is OK.
> >
> > What I meant that calling wait_on_page_locked() on !PageUptodate() page
> > will likely make it up-to-date and we don't need to SCAN_FAIL the attempt.
> >
>
> Yeah, I got the point. My only concern is that I don't know how to
> reliably trigger this case for testing. I can try to trigger it. But I
> don't know whether it will happen easily.
Atrifically slowing down IO should do the trick.
--
Kirill A. Shutemov
next prev parent reply other threads:[~2019-06-24 15:15 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-06-23 5:47 [PATCH v7 0/6] Enable THP for text section of non-shmem files Song Liu
2019-06-23 5:47 ` [PATCH v7 1/6] filemap: check compound_head(page)->mapping in filemap_fault() Song Liu
2019-06-23 5:47 ` [PATCH v7 2/6] filemap: update offset check " Song Liu
2019-06-23 5:47 ` [PATCH v7 3/6] mm,thp: stats for file backed THP Song Liu
2019-06-23 5:47 ` [PATCH v7 4/6] khugepaged: rename collapse_shmem() and khugepaged_scan_shmem() Song Liu
2019-06-23 5:47 ` [PATCH v7 5/6] mm,thp: add read-only THP support for (non-shmem) FS Song Liu
2019-06-24 12:47 ` Kirill A. Shutemov
2019-06-24 14:01 ` Song Liu
2019-06-24 14:27 ` Kirill A. Shutemov
2019-06-24 14:42 ` Song Liu
2019-06-24 14:54 ` Kirill A. Shutemov
2019-06-24 15:04 ` Song Liu
2019-06-24 15:15 ` Kirill A. Shutemov [this message]
2019-06-24 16:33 ` Song Liu
2019-06-23 5:47 ` [PATCH v7 6/6] mm,thp: avoid writes to file with THP in pagecache Song Liu
2019-06-24 12:49 ` Kirill A. Shutemov
2019-06-24 14:01 ` Song Liu
[not found] <20190624031604.7764-1-hdanton@sina.com>
2019-06-24 4:27 ` [PATCH v7 5/6] mm,thp: add read-only THP support for (non-shmem) FS Song Liu
[not found] <20190624074816.10992-1-hdanton@sina.com>
2019-06-24 21:17 ` [PATCH v7 5/6] mm,thp: add read-only THP support for (non-shmem)FS Song Liu
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