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[90.235.24.7]) by smtp.gmail.com with ESMTPSA id f17-20020a2e6a11000000b00282cffdfe6asm3326139ljc.61.2023.01.16.03.44.43 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 16 Jan 2023 03:44:44 -0800 (PST) From: Uladzislau Rezki X-Google-Original-From: Uladzislau Rezki Date: Mon, 16 Jan 2023 12:44:42 +0100 To: Baoquan He Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, urezki@gmail.com, lstoakes@gmail.com, stephen.s.brennan@oracle.com, willy@infradead.org, akpm@linux-foundation.org, hch@infradead.org Subject: Re: [PATCH v3 5/7] mm/vmalloc: skip the uninitilized vmalloc areas Message-ID: References: <20230113031921.64716-1-bhe@redhat.com> <20230113031921.64716-6-bhe@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20230113031921.64716-6-bhe@redhat.com> X-Rspam-User: X-Rspamd-Server: rspam03 X-Stat-Signature: izhqao8fuimemzp8fd7bfku3pyeycp5a X-Rspamd-Queue-Id: 6D7E31C0015 X-HE-Tag: 1673869486-28429 X-HE-Meta: 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 fOqCo3L0 CN6u+YralZaLNdEHzK9Q3fVybG/xLje8spvCF3j/WxXKgZkDkav3CD7gMtnqyEPzqfKESY2XBbwYzRmHLUoAAnzxk/Q== 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 Fri, Jan 13, 2023 at 11:19:19AM +0800, Baoquan He wrote: > For areas allocated via vmalloc_xxx() APIs, it searches for unmapped area > to reserve and allocates new pages to map into, please see function > __vmalloc_node_range(). During the process, flag VM_UNINITIALIZED is set > in vm->flags to indicate that the pages allocation and mapping haven't > been done, until clear_vm_uninitialized_flag() is called to clear it. > > For this kind of area, if VM_UNINITIALIZED is still set, let's ignore > it in vread() because pages newly allocated and being mapped in that > area only contains zero data. reading them out by aligned_vread() is > wasting time. > > Signed-off-by: Baoquan He > --- > mm/vmalloc.c | 5 +++++ > 1 file changed, 5 insertions(+) > > diff --git a/mm/vmalloc.c b/mm/vmalloc.c > index 4a10b3b692fa..dbcdcad2276b 100644 > --- a/mm/vmalloc.c > +++ b/mm/vmalloc.c > @@ -3660,6 +3660,11 @@ long vread(char *buf, char *addr, unsigned long count) > if (!vm && !flags) > continue; > > + if (vm && (vm->flags & VM_UNINITIALIZED)) > + continue; > + /* Pair with smp_wmb() in clear_vm_uninitialized_flag() */ > + smp_rmb(); > + > vaddr = (char *) va->va_start; > size = vm ? get_vm_area_size(vm) : va_size(va); > > -- > 2.34.1 > Reviewed-by: Uladzislau Rezki (Sony) -- Uladzislau Rezki