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a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=kj0WDd7GW3ZafwLkwvjtKCJlLdXVHYFvSyIRNFPhhJs=; b=WzPG3OZUt7Q+SxqgRJDyOBsfXurnqU1bhNHdXIXZn+5b9Qh0V5onugwBVmrwa2B0bs qLYU2opsmPWW2N1DrkX6110oi3/twis7J7NLip6W/NmUTf7DMB8nUsCpYz7WCHNz2jAW 73ZQkoHqKhK8fIqHG/uRk0OHJUyjM/ftEzQ8TIvi/OWyohWiOPg6XHAZ38luo9gefywx fpjhtlyy7wo6ZaItQsMUJGgV1cC2yovH3nO71Nkbtz2if+eE/Ug28qKxjVve39NFI+00 YSvnBrV/eTmpwqYUextxKLe4xSaHlRO5MBGf/V9jOnpaEr/in2UA/Rs4yh6pYq43djDJ jaVg== X-Gm-Message-State: AOAM533ch4XQZh5H5mUqwTHSa9ovj2MhS2Xefj4pRxIk1xqXahigRED5 9l2JC952/y+jFQfYm8YqX9CNgfv6Pabkr86WpwgIdw== X-Google-Smtp-Source: ABdhPJwAnnOF1DfZ6tU3qBpyxbXObsyrOi0H0yApKcnJAOa41sGtBxbjPtLnlPuc9h4FZRo23mRNTy2PVNoHj1uSHWE= X-Received: by 2002:a62:16c1:0:b029:18c:8a64:fc04 with SMTP id 184-20020a6216c10000b029018c8a64fc04mr3535171pfw.59.1606216113637; Tue, 24 Nov 2020 03:08:33 -0800 (PST) MIME-Version: 1.0 References: <20201124095259.58755-1-songmuchun@bytedance.com> <20201124095259.58755-15-songmuchun@bytedance.com> <5f6443f10292405d813ffb444ef315fc@hisilicon.com> In-Reply-To: <5f6443f10292405d813ffb444ef315fc@hisilicon.com> From: Muchun Song Date: Tue, 24 Nov 2020 19:07:56 +0800 Message-ID: Subject: Re: [External] RE: [PATCH v6 14/16] mm/hugetlb: Add a kernel parameter hugetlb_free_vmemmap To: "Song Bao Hua (Barry Song)" Cc: "corbet@lwn.net" , "mike.kravetz@oracle.com" , "tglx@linutronix.de" , "mingo@redhat.com" , "bp@alien8.de" , "x86@kernel.org" , "hpa@zytor.com" , "dave.hansen@linux.intel.com" , "luto@kernel.org" , "peterz@infradead.org" , "viro@zeniv.linux.org.uk" , "akpm@linux-foundation.org" , "paulmck@kernel.org" , "mchehab+huawei@kernel.org" , "pawan.kumar.gupta@linux.intel.com" , "rdunlap@infradead.org" , "oneukum@suse.com" , "anshuman.khandual@arm.com" , "jroedel@suse.de" , "almasrymina@google.com" , "rientjes@google.com" , "willy@infradead.org" , "osalvador@suse.de" , "mhocko@suse.com" , "duanxiongchun@bytedance.com" , "linux-doc@vger.kernel.org" , "linux-kernel@vger.kernel.org" , "linux-mm@kvack.org" , "linux-fsdevel@vger.kernel.org" Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Nov 24, 2020 at 6:54 PM Song Bao Hua (Barry Song) wrote: > > > > > -----Original Message----- > > From: Muchun Song [mailto:songmuchun@bytedance.com] > > Sent: Tuesday, November 24, 2020 10:53 PM > > To: corbet@lwn.net; mike.kravetz@oracle.com; tglx@linutronix.de; > > mingo@redhat.com; bp@alien8.de; x86@kernel.org; hpa@zytor.com; > > dave.hansen@linux.intel.com; luto@kernel.org; peterz@infradead.org; > > viro@zeniv.linux.org.uk; akpm@linux-foundation.org; paulmck@kernel.org; > > mchehab+huawei@kernel.org; pawan.kumar.gupta@linux.intel.com; > > rdunlap@infradead.org; oneukum@suse.com; anshuman.khandual@arm.com; > > jroedel@suse.de; almasrymina@google.com; rientjes@google.com; > > willy@infradead.org; osalvador@suse.de; mhocko@suse.com; Song Bao Hua > > (Barry Song) > > Cc: duanxiongchun@bytedance.com; linux-doc@vger.kernel.org; > > linux-kernel@vger.kernel.org; linux-mm@kvack.org; > > linux-fsdevel@vger.kernel.org; Muchun Song > > Subject: [PATCH v6 14/16] mm/hugetlb: Add a kernel parameter > > hugetlb_free_vmemmap > > > > Add a kernel parameter hugetlb_free_vmemmap to disable the feature of > > freeing unused vmemmap pages associated with each hugetlb page on boot. > > > > Signed-off-by: Muchun Song > > --- > > Documentation/admin-guide/kernel-parameters.txt | 9 +++++++++ > > Documentation/admin-guide/mm/hugetlbpage.rst | 3 +++ > > mm/hugetlb_vmemmap.c | 19 > > ++++++++++++++++++- > > 3 files changed, 30 insertions(+), 1 deletion(-) > > > > diff --git a/Documentation/admin-guide/kernel-parameters.txt > > b/Documentation/admin-guide/kernel-parameters.txt > > index 5debfe238027..d28c3acde965 100644 > > --- a/Documentation/admin-guide/kernel-parameters.txt > > +++ b/Documentation/admin-guide/kernel-parameters.txt > > @@ -1551,6 +1551,15 @@ > > Documentation/admin-guide/mm/hugetlbpage.rst. > > Format: size[KMG] > > > > + hugetlb_free_vmemmap= > > + [KNL] When CONFIG_HUGETLB_PAGE_FREE_VMEMMAP is set, > > + this controls freeing unused vmemmap pages associated > > + with each HugeTLB page. > > + Format: { on | off (default) } > > + > > + on: enable the feature > > + off: disable the feature > > + > > We've a parameter here. but wouldn't it be applied to "x86/mm/64/:disable > Pmd page mapping of vmemmap" as well? > If (hugetlb_free_vmemmap_enabled) > Do Basepage mapping? Oh, yeah, we can. Thanks. > > > hung_task_panic= > > [KNL] Should the hung task detector generate panics. > > Format: 0 | 1 > > diff --git a/Documentation/admin-guide/mm/hugetlbpage.rst > > b/Documentation/admin-guide/mm/hugetlbpage.rst > > index f7b1c7462991..6a8b57f6d3b7 100644 > > --- a/Documentation/admin-guide/mm/hugetlbpage.rst > > +++ b/Documentation/admin-guide/mm/hugetlbpage.rst > > @@ -145,6 +145,9 @@ default_hugepagesz > > > > will all result in 256 2M huge pages being allocated. Valid default > > huge page size is architecture dependent. > > +hugetlb_free_vmemmap > > + When CONFIG_HUGETLB_PAGE_FREE_VMEMMAP is set, this enables > > freeing > > + unused vmemmap pages associated each HugeTLB page. > > > > When multiple huge page sizes are supported, ``/proc/sys/vm/nr_hugepages`` > > indicates the current number of pre-allocated huge pages of the default size. > > diff --git a/mm/hugetlb_vmemmap.c b/mm/hugetlb_vmemmap.c > > index 509ca451e232..b2222f8d1245 100644 > > --- a/mm/hugetlb_vmemmap.c > > +++ b/mm/hugetlb_vmemmap.c > > @@ -131,6 +131,22 @@ typedef void (*vmemmap_pte_remap_func_t)(struct > > page *reuse, pte_t *ptep, > > unsigned long start, unsigned long end, > > void *priv); > > > > +static bool hugetlb_free_vmemmap_enabled __initdata; > > + > > +static int __init early_hugetlb_free_vmemmap_param(char *buf) > > +{ > > + if (!buf) > > + return -EINVAL; > > + > > + if (!strcmp(buf, "on")) > > + hugetlb_free_vmemmap_enabled = true; > > + else if (strcmp(buf, "off")) > > + return -EINVAL; > > + > > + return 0; > > +} > > +early_param("hugetlb_free_vmemmap", > > early_hugetlb_free_vmemmap_param); > > + > > static inline unsigned int vmemmap_pages_per_hpage(struct hstate *h) > > { > > return free_vmemmap_pages_per_hpage(h) + RESERVE_VMEMMAP_NR; > > @@ -322,7 +338,8 @@ void __init hugetlb_vmemmap_init(struct hstate *h) > > unsigned int order = huge_page_order(h); > > unsigned int vmemmap_pages; > > > > - if (!is_power_of_2(sizeof(struct page))) { > > + if (!is_power_of_2(sizeof(struct page)) || > > + !hugetlb_free_vmemmap_enabled) { > > pr_info("disable freeing vmemmap pages for %s\n", h->name); > > return; > > } > > -- > > 2.11.0 > > Thanks > Barry > -- Yours, Muchun