linux-kernel - Re: [Bug 11046] New: Kernel bug in mm/bootmem.c on Sparc machines

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Message-Id: <20080724.145901.247647559.davem@davemloft.net>
Date:	Thu, 24 Jul 2008 14:59:01 -0700 (PDT)
From:	David Miller <davem@...emloft.net>
To:	hannes@...urebad.de
Cc:	akpm@...ux-foundation.org, sparclinux@...r.kernel.org,
	bugme-daemon@...zilla.kernel.org, lomp0101@....net,
	linux-kernel@...r.kernel.org
Subject: Re: [Bug 11046] New: Kernel bug in mm/bootmem.c on Sparc machines

From: Johannes Weiner <hannes@...urebad.de>
Date: Thu, 24 Jul 2008 23:32:06 +0200

> Sorry, Dave, I missed that before: there is still the BUG_ON() in
> can_reserve_bootmem_core(), which should just return 0 instead.
> 
> Other than that, yes, Andrew, this introduces the same behaviour the
> bootmem rewrite.

Thanks, here is an updated version of the patch:

bootmem: Allow zero length reserve and free.

It's either this or all the call sites explicitly check
when such a case is possible and sometimes expected.

Signed-off-by: David S. Miller <davem@...emloft.net>

diff --git a/mm/bootmem.c b/mm/bootmem.c
index 8d9f60e..5e3fab8 100644
--- a/mm/bootmem.c
+++ b/mm/bootmem.c
@@ -117,7 +117,8 @@ static int __init can_reserve_bootmem_core(bootmem_data_t *bdata,
 	unsigned long sidx, eidx;
 	unsigned long i;
 
-	BUG_ON(!size);
+	if (!size)
+		return 0;
 
 	/* out of range, don't hold other */
 	if (addr + size < bdata->node_boot_start ||
@@ -153,7 +154,8 @@ static void __init reserve_bootmem_core(bootmem_data_t *bdata,
 	unsigned long sidx, eidx;
 	unsigned long i;
 
-	BUG_ON(!size);
+	if (!size)
+		return;
 
 	/* out of range */
 	if (addr + size < bdata->node_boot_start ||
@@ -187,7 +189,8 @@ static void __init free_bootmem_core(bootmem_data_t *bdata, unsigned long addr,
 	unsigned long sidx, eidx;
 	unsigned long i;
 
-	BUG_ON(!size);
+	if (!size)
+		return;
 
 	/* out range */
 	if (addr + size < bdata->node_boot_start ||
--
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