From: "Kirill A. Shutemov" <kirill@shutemov.name>
To: Song Liu <songliubraving@fb.com>
Cc: LKML <linux-kernel@vger.kernel.org>,
"linux-mm@kvack.org" <linux-mm@kvack.org>,
"namit@vmware.com" <namit@vmware.com>,
"peterz@infradead.org" <peterz@infradead.org>,
"oleg@redhat.com" <oleg@redhat.com>,
"rostedt@goodmis.org" <rostedt@goodmis.org>,
"mhiramat@kernel.org" <mhiramat@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>
Subject: Re: [PATCH v3 3/5] mm, thp: introduce FOLL_SPLIT_PMD
Date: Thu, 13 Jun 2019 17:16:15 +0300 [thread overview]
Message-ID: <20190613141615.yvmckzi3fac4qjag@box> (raw)
In-Reply-To: <5A80A2B9-51C3-49C4-97B6-33889CC47F08@fb.com>
On Thu, Jun 13, 2019 at 01:57:30PM +0000, Song Liu wrote:
> > And I'm not convinced that it belongs here at all. User requested PMD
> > split and it is done after split_huge_pmd(). The rest can be handled by
> > the caller as needed.
>
> I put this part here because split_huge_pmd() for file-backed THP is
> not really done after split_huge_pmd(). And I would like it done before
> calling follow_page_pte() below. Maybe we can still do them here, just
> for file-backed THPs?
>
> If we would move it, shall we move to callers of follow_page_mask()?
> In that case, we will probably end up with similar code in two places:
> __get_user_pages() and follow_page().
>
> Did I get this right?
Would it be enough to replace pte_offset_map_lock() in follow_page_pte()
with pte_alloc_map_lock()?
This will leave bunch not populated PTE entries, but it is fine: they will
be populated on the next access to them.
--
Kirill A. Shutemov
next prev parent reply other threads:[~2019-06-13 14:16 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-06-12 22:03 [PATCH v3 0/5] THP aware uprobe Song Liu
2019-06-12 22:03 ` [PATCH v3 1/5] mm: move memcmp_pages() and pages_identical() Song Liu
2019-06-12 22:03 ` [PATCH v3 2/5] uprobe: use original page when all uprobes are removed Song Liu
2019-06-12 22:03 ` [PATCH v3 3/5] mm, thp: introduce FOLL_SPLIT_PMD Song Liu
2019-06-13 12:57 ` Kirill A. Shutemov
2019-06-13 13:57 ` Song Liu
2019-06-13 14:16 ` Kirill A. Shutemov [this message]
2019-06-13 15:03 ` Song Liu
2019-06-13 15:14 ` Kirill A. Shutemov
2019-06-13 15:24 ` Song Liu
2019-06-13 16:47 ` Song Liu
2019-06-13 17:42 ` Song Liu
2019-06-12 22:03 ` [PATCH v3 4/5] uprobe: use FOLL_SPLIT_PMD instead of FOLL_SPLIT Song Liu
2019-06-12 22:03 ` [PATCH v3 5/5] uprobe: collapse THP pmd after removing all uprobes Song Liu
2019-06-12 22:03 ` [PATCH v3 6/6] mm, thp: introduce FOLL_SPLIT_PMD Song Liu
2019-06-12 22:16 ` Song Liu
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