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[37.188.173.135]) by smtp.gmail.com with ESMTPSA id g3sm25628896wrb.46.2020.06.23.08.18.29 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 23 Jun 2020 08:18:30 -0700 (PDT) Date: Tue, 23 Jun 2020 17:18:28 +0200 From: Michal Hocko To: Wei Yang Cc: akpm@linux-foundation.org, osalvador@suse.de, dan.j.williams@intel.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org, david@redhat.com Subject: Re: [PATCH] mm/spase: never partially remove memmap for early section Message-ID: <20200623151828.GA31426@dhcp22.suse.cz> References: <20200623094258.6705-1-richard.weiyang@linux.alibaba.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200623094258.6705-1-richard.weiyang@linux.alibaba.com> X-Rspamd-Queue-Id: D55AE100A4374 X-Spamd-Result: default: False [0.00 / 100.00] X-Rspamd-Server: rspam05 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 Tue 23-06-20 17:42:58, Wei Yang wrote: > For early sections, we assumes its memmap will never be partially > removed. But current behavior breaks this. > > Let's correct it. > > Fixes: ba72b4c8cf60 ("mm/sparsemem: support sub-section hotplug") > Signed-off-by: Wei Yang Can a user trigger this or is this a theoretical bug? > --- > mm/sparse.c | 6 +++--- > 1 file changed, 3 insertions(+), 3 deletions(-) > > diff --git a/mm/sparse.c b/mm/sparse.c > index b2b9a3e34696..1a0069f492f5 100644 > --- a/mm/sparse.c > +++ b/mm/sparse.c > @@ -825,10 +825,10 @@ static void section_deactivate(unsigned long pfn, unsigned long nr_pages, > ms->section_mem_map &= ~SECTION_HAS_MEM_MAP; > } > > - if (section_is_early && memmap) > - free_map_bootmem(memmap); > - else > + if (!section_is_early) This begs a comment. > depopulate_section_memmap(pfn, nr_pages, altmap); > + else if (memmap) > + free_map_bootmem(memmap); > > if (empty) > ms->section_mem_map = (unsigned long)NULL; > -- > 2.20.1 (Apple Git-117) > -- Michal Hocko SUSE Labs