linux-kernel - Re: [PATCH 1/4] mm/pgtable: Fix continue to preallocate pmds even if failure occurrence

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Message-ID: <520D160A.10405@intel.com>
Date:	Thu, 15 Aug 2013 10:55:22 -0700
From:	Dave Hansen <dave.hansen@...el.com>
To:	Wanpeng Li <liwanp@...ux.vnet.ibm.com>
CC:	Andrew Morton <akpm@...ux-foundation.org>,
	Rik van Riel <riel@...hat.com>,
	Dave Hansen <dave.hansen@...ux.intel.com>,
	Fengguang Wu <fengguang.wu@...el.com>,
	Joonsoo Kim <iamjoonsoo.kim@....com>,
	Johannes Weiner <hannes@...xchg.org>,
	Tejun Heo <tj@...nel.org>,
	Yasuaki Ishimatsu <isimatu.yasuaki@...fujitsu.com>,
	David Rientjes <rientjes@...gle.com>,
	KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com>,
	Jiri Kosina <jkosina@...e.cz>, linux-mm@...ck.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/4] mm/pgtable: Fix continue to preallocate pmds even
 if failure occurrence

On 08/14/2013 05:31 PM, Wanpeng Li wrote:
> preallocate_pmds will continue to preallocate pmds even if failure 
> occurrence, and then free all the preallocate pmds if there is 
> failure, this patch fix it by stop preallocate if failure occurrence
> and go to free path.

I guess there are a billion ways to do this, but I'm not sure we even
need 'failed':

--- arch/x86/mm/pgtable.c.orig	2013-08-15 10:52:15.145615027 -0700
+++ arch/x86/mm/pgtable.c	2013-08-15 10:52:47.509614081 -0700
@@ -196,21 +196,18 @@
 static int preallocate_pmds(pmd_t *pmds[])
 {
 	int i;
-	bool failed = false;

 	for(i = 0; i < PREALLOCATED_PMDS; i++) {
 		pmd_t *pmd = (pmd_t *)__get_free_page(PGALLOC_GFP);
 		if (pmd == NULL)
-			failed = true;
+			goto err;
 		pmds[i] = pmd;
 	}

-	if (failed) {
-		free_pmds(pmds);
-		return -ENOMEM;
-	}
-
 	return 0;
+err:
+	free_pmds(pmds);
+	return -ENOMEM;
 }

I don't have a problem with what you have, though.  It's better than
what was there, so:

Reviewed-by: Dave Hansen <dave.hansen@...ux.intel.com>
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