Another: [PATCH} 2.6 ppc64 rtas crash in kmalloc

[Linas Vepstas]

Hi,

Another bounced patch email.

--linas

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Date: Tue, 13 Jul 2004 18:29:45 -0500
To: paulus at au1.ibm.com, paulus at samba.org
Cc: linuxppc64-dev at lists.linuxppc.org
Subject: [PATCH} 2.6 ppc64 rtas crash in kmalloc
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From: Linas Vepstas <linas at bilge>


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Paul,

Please review and send upstream as appropriate.

The recent set of rtas patches I sent in (about a week ago)
introduced a bug: the possible use of kmalloc before the
VM subsystem is initialized.  This patch checks for the VM
subsystem being ready, and avoids the kmalloc if its not.

People typically hit this bug during very early boot stages,
when EEH is being initialized, and an rtas_call fails, leading
to the use of kmalloc to get the error message.

--linas



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===== arch/ppc64/kernel/rtas.c 1.37 vs edited =====
--- 1.37/arch/ppc64/kernel/rtas.c	Mon Jul  5 05:27:10 2004
+++ edited/arch/ppc64/kernel/rtas.c	Tue Jul 13 18:12:06 2004
@@ -165,9 +165,13 @@

 	/* Log the error in the unlikely case that there was one. */
 	if (unlikely(logit)) {
-		buff_copy = kmalloc(RTAS_ERROR_LOG_MAX, GFP_ATOMIC);
-		if (buff_copy) {
-			memcpy(buff_copy, rtas_err_buf, RTAS_ERROR_LOG_MAX);
+		/* Can't call kmalloc if VM subsystem is not yet up. */
+		struct cache_sizes *csizep = malloc_sizes;
+		if (csizep->cs_cachep) {
+			buff_copy = kmalloc(RTAS_ERROR_LOG_MAX, GFP_ATOMIC);
+			if (buff_copy) {
+				memcpy(buff_copy, rtas_err_buf, RTAS_ERROR_LOG_MAX);
+			}
 		}
 	}


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