linux-kernel - Re: [REGRESSION] boot regression in next-20170428

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Message-Id: <20170428.120603.1882981347971536826.davem@davemloft.net>
Date:   Fri, 28 Apr 2017 12:06:03 -0400 (EDT)
From:   David Miller <davem@...emloft.net>
To:     niklas.cassel@...s.com
Cc:     herbert@...dor.apana.org.au, linux-kernel@...r.kernel.org
Subject: Re: [REGRESSION] boot regression in next-20170428

From: Niklas Cassel <niklas.cassel@...s.com>
Date: Fri, 28 Apr 2017 17:08:17 +0200

> Hello
> 
> 
> Since next-20170428
> the ARTPEC-6 SoC (MACH_ARTPEC6) does no longer boot.
> 
> It works fine with next-20170427.
> 
> 
> I've bisected it to the following commit:
> 
> 6d684e54690caef45cf14051ddeb7c71beeb681b is the first bad commit
> commit 6d684e54690caef45cf14051ddeb7c71beeb681b
> Author: Herbert Xu <herbert@...dor.apana.org.au>
> Date:   Thu Apr 27 13:44:51 2017 +0800
> 
>     rhashtable: Cap total number of entries to 2^31

Fixed by:

>From 2d2ab658d2debcb4c0e29c9e6f18e5683f3077bf Mon Sep 17 00:00:00 2001
From: Herbert Xu <herbert@...dor.apana.org.au>
Date: Fri, 28 Apr 2017 14:10:48 +0800
Subject: [PATCH] rhashtable: Do not lower max_elems when max_size is zero

The commit 6d684e54690c ("rhashtable: Cap total number of entries
to 2^31") breaks rhashtable users that do not set max_size.  This
is because when max_size is zero max_elems is also incorrectly set
to zero instead of 2^31.

This patch fixes it by only lowering max_elems when max_size is not
zero.

Fixes: 6d684e54690c ("rhashtable: Cap total number of entries to 2^31")
Reported-by: Florian Fainelli <f.fainelli@...il.com>
Reported-by: kernel test robot <fengguang.wu@...el.com>
Signed-off-by: Herbert Xu <herbert@...dor.apana.org.au>
Signed-off-by: David S. Miller <davem@...emloft.net>
---
 lib/rhashtable.c | 11 ++++++-----
 1 file changed, 6 insertions(+), 5 deletions(-)

diff --git a/lib/rhashtable.c b/lib/rhashtable.c
index 751630b..3895486 100644
--- a/lib/rhashtable.c
+++ b/lib/rhashtable.c
@@ -958,13 +958,14 @@ int rhashtable_init(struct rhashtable *ht,
 	if (params->min_size)
 		ht->p.min_size = roundup_pow_of_two(params->min_size);
 
-	if (params->max_size)
-		ht->p.max_size = rounddown_pow_of_two(params->max_size);
-
 	/* Cap total entries at 2^31 to avoid nelems overflow. */
 	ht->max_elems = 1u << 31;
-	if (ht->p.max_size < ht->max_elems / 2)
-		ht->max_elems = ht->p.max_size * 2;
+
+	if (params->max_size) {
+		ht->p.max_size = rounddown_pow_of_two(params->max_size);
+		if (ht->p.max_size < ht->max_elems / 2)
+			ht->max_elems = ht->p.max_size * 2;
+	}
 
 	ht->p.min_size = max(ht->p.min_size, HASH_MIN_SIZE);
 
-- 
2.4.11