From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx156.postini.com [74.125.245.156]) by kanga.kvack.org (Postfix) with SMTP id 3287E6B0039 for ; Thu, 18 Apr 2013 19:33:39 -0400 (EDT) Received: from m2.gw.fujitsu.co.jp (unknown [10.0.50.72]) by fgwmail5.fujitsu.co.jp (Postfix) with ESMTP id BE80D3EE0C0 for ; Fri, 19 Apr 2013 08:33:37 +0900 (JST) Received: from smail (m2 [127.0.0.1]) by outgoing.m2.gw.fujitsu.co.jp (Postfix) with ESMTP id A100A45DE4D for ; Fri, 19 Apr 2013 08:33:37 +0900 (JST) Received: from s2.gw.fujitsu.co.jp (s2.gw.fujitsu.co.jp [10.0.50.92]) by m2.gw.fujitsu.co.jp (Postfix) with ESMTP id 7CDFB45DD78 for ; Fri, 19 Apr 2013 08:33:37 +0900 (JST) Received: from s2.gw.fujitsu.co.jp (localhost.localdomain [127.0.0.1]) by s2.gw.fujitsu.co.jp (Postfix) with ESMTP id 6B4631DB803F for ; Fri, 19 Apr 2013 08:33:37 +0900 (JST) Received: from G01JPEXCHYT13.g01.fujitsu.local (G01JPEXCHYT13.g01.fujitsu.local [10.128.194.52]) by s2.gw.fujitsu.co.jp (Postfix) with ESMTP id 14ECA1DB803C for ; Fri, 19 Apr 2013 08:33:37 +0900 (JST) Message-ID: <517082B9.7050708@jp.fujitsu.com> Date: Fri, 19 Apr 2013 08:33:13 +0900 From: Yasuaki Ishimatsu MIME-Version: 1.0 Subject: Re: [Bug fix PATCH v4] Reusing a resource structure allocated by bootmem References: <516FB07C.9010603@jp.fujitsu.com> <1366295000.3824.47.camel@misato.fc.hp.com> In-Reply-To: <1366295000.3824.47.camel@misato.fc.hp.com> Content-Type: text/plain; charset="UTF-8"; format=flowed Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Toshi Kani Cc: akpm@linux-foundation.org, linuxram@us.ibm.com, rientjes@google.com, linux-kernel@vger.kernel.org, linux-mm@kvack.org Hi Toshi, 2013/04/18 23:23, Toshi Kani wrote: > On Thu, 2013-04-18 at 17:36 +0900, Yasuaki Ishimatsu wrote: >> When hot removing memory presented at boot time, following messages are shown: > : >> diff --git a/kernel/resource.c b/kernel/resource.c >> index 4aef886..637e8d2 100644 >> --- a/kernel/resource.c >> +++ b/kernel/resource.c >> @@ -21,6 +21,7 @@ >> #include >> #include >> #include >> +#include >> #include >> >> >> @@ -50,6 +51,16 @@ struct resource_constraint { >> >> static DEFINE_RWLOCK(resource_lock); >> >> +/* >> + * For memory hotplug, there is no way to free resource entries allocated >> + * by boot mem after the system is up. So for reusing the resource entry >> + * we need to remember the resource. >> + */ >> +struct resource bootmem_resource = { >> + .sibling = NULL, >> +}; > > This should be a pointer of struct resource and declared as static, such > as: > > static struct resource *bootmem_resource_free; O.K. I'll update it. > >> +static DEFINE_SPINLOCK(bootmem_resource_lock); >> + >> static void *r_next(struct seq_file *m, void *v, loff_t *pos) >> { >> struct resource *p = v; >> @@ -151,6 +162,39 @@ __initcall(ioresources_init); >> >> #endif /* CONFIG_PROC_FS */ >> >> +static void free_resource(struct resource *res) >> +{ >> + if (!res) >> + return; >> + >> + if (PageSlab(virt_to_head_page(res))) { >> + spin_lock(&bootmem_resource_lock); >> + res->sibling = bootmem_resource.sibling; >> + bootmem_resource.sibling = res; >> + spin_unlock(&bootmem_resource_lock); >> + } else { >> + kfree(res); >> + } >> +} > > I second with Johannes. I'll update it. > >> +static struct resource *get_resource(gfp_t flags) >> +{ >> + struct resource *res = NULL; >> + >> + spin_lock(&bootmem_resource_lock); >> + if (bootmem_resource.sibling) { >> + res = bootmem_resource.sibling; >> + bootmem_resource.sibling = res->sibling; >> + memset(res, 0, sizeof(struct resource)); >> + } >> + spin_unlock(&bootmem_resource_lock); > > I prefer to keep memset() outside of the spin lock. > > spin_lock(&bootmem_resource_lock); > if (..) { > : > spin_unlock(&bootmem_resource_lock); > memset(res, 0, sizeof(struct resource)); > } else { > spin_unlock(&bootmem_resource_lock); > res = kzalloc(sizeof(struct resource), flags); > } Hmm. It is a little ugly. How about it? spin_lock(&bootmem_resource_lock); if (bootmem_resource.sibling) { res = bootmem_resource.sibling; bootmem_resource.sibling = res->sibling; } spin_unlock(&bootmem_resource_lock); if (res) memset(res, 0, sizeof(struct resource)); else res = kzalloc(sizeof(struct resource), flags); Thanks, Yasuaki Ishimatsu > > Thanks, > -Toshi > >> + >> + >> + return res; >> +} >> + > > -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org