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Shutemov" To: Song Liu Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org, namit@vmware.com, peterz@infradead.org, oleg@redhat.com, rostedt@goodmis.org, mhiramat@kernel.org, matthew.wilcox@oracle.com, kirill.shutemov@linux.intel.com, kernel-team@fb.com, william.kucharski@oracle.com, chad.mynhier@oracle.com, mike.kravetz@oracle.com Subject: Re: [PATCH uprobe, thp 4/4] uprobe: collapse THP pmd after removing all uprobes Message-ID: <20190530122055.xzlbo3wfpqtmo2fw@box> References: <20190529212049.2413886-1-songliubraving@fb.com> <20190529212049.2413886-5-songliubraving@fb.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190529212049.2413886-5-songliubraving@fb.com> User-Agent: NeoMutt/20180716 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Wed, May 29, 2019 at 02:20:49PM -0700, Song Liu wrote: > After all uprobes are removed from the huge page (with PTE pgtable), it > is possible to collapse the pmd and benefit from THP again. This patch > does the collapse. I don't think it's right way to go. We should deferred it to khugepaged. We need to teach khugepaged to deal with PTE-mapped compound page. And uprobe should only kick khugepaged for a VMA. Maybe synchronously. -- Kirill A. Shutemov