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Tue, 10 Mar 2020 15:24:10 -0700 (PDT) Date: Tue, 10 Mar 2020 15:24:08 -0700 From: Minchan Kim To: Vlastimil Babka Cc: Andrew Morton , LKML , linux-mm , linux-api@vger.kernel.org, oleksandr@redhat.com, Suren Baghdasaryan , Tim Murray , Daniel Colascione , Sandeep Patil , Sonny Rao , Brian Geffon , Michal Hocko , Johannes Weiner , Shakeel Butt , John Dias , Joel Fernandes , Jann Horn , alexander.h.duyck@linux.intel.com, sj38.park@gmail.com Subject: Re: [PATCH v7 3/7] mm: check fatal signal pending of target process Message-ID: <20200310222408.GC72963@google.com> References: <20200302193630.68771-1-minchan@kernel.org> <20200302193630.68771-4-minchan@kernel.org> <2f3a9530-483d-0861-3844-bc12d212dd93@suse.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <2f3a9530-483d-0861-3844-bc12d212dd93@suse.cz> User-Agent: Mutt/1.12.2 (2019-09-21) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Mar 06, 2020 at 11:22:07AM +0100, Vlastimil Babka wrote: > On 3/2/20 8:36 PM, Minchan Kim wrote: > > Bail out to prevent unnecessary CPU overhead if target process has > > pending fatal signal during (MADV_COLD|MADV_PAGEOUT) operation. > > > > Reviewed-by: Suren Baghdasaryan > > Signed-off-by: Minchan Kim > > Reviewed-by: Vlastimil Babka > > Nit below: > > > --- > > mm/madvise.c | 29 +++++++++++++++++++++-------- > > 1 file changed, 21 insertions(+), 8 deletions(-) > > > > diff --git a/mm/madvise.c b/mm/madvise.c > > index 349473fc6683..6543f2bfc3d8 100644 > > --- a/mm/madvise.c > > +++ b/mm/madvise.c > > @@ -36,6 +36,7 @@ > > struct madvise_walk_private { > > struct mmu_gather *tlb; > > bool pageout; > > + struct task_struct *target_task; > > }; > > > > /* > > @@ -316,6 +317,10 @@ static int madvise_cold_or_pageout_pte_range(pmd_t *pmd, > > if (fatal_signal_pending(current)) > > return -EINTR; > > > > + if (private->target_task && > > + fatal_signal_pending(private->target_task)) > > + return -EINTR; > > With madvise(2) private->target_task will be current, thus current will be > tested twice. Not wrong, but maybe add a "private->target_task != current" > condition? It was in old series but removed because reviewer(IIRC, suren) wanted it. I am not strong preference either way. Since you said it's nit and considering other reviewer wanted to remove it, I will not change further. Thanks!