Hello,
while working on the upcoming SLES11 SP2, I ran into an issue with booting the
panic kernel on a kernel crash. In the first iteration I found out that the
initial register backing store gets overwritten with zeroes, causing a kernel
crash shortly afterwards.
Further investigation revealed that rsvd_region[] contains overlapping
entries: find_memmap_space() returns a pointer which lies between KERNEL_START
and _end. This is correct with the EFI memmap as patched by the kexec
purgatory code. That code removes vmlinux LOAD segments from the usable map,
but there is a pretty large hole between the gate section and the per-cpu
section.
With the following patch, the panic kernel can boot and save the crash dump.
Signed-off-by: Petr Tesarik <ptesarik@xxxxxxx>
--- a/arch/ia64/kernel/setup.c
+++ b/arch/ia64/kernel/setup.c
@@ -225,6 +225,23 @@
}
}
+/* merge overlaps */
+static int __init
+merge_regions (struct rsvd_region *rsvd_region, int max)
+{
+ int i;
+ for (i = 1; i < max; ++i) {
+ if (rsvd_region[i].start >= rsvd_region[i-1].end)
+ continue;
+ if (rsvd_region[i].end > rsvd_region[i-1].end)
+ rsvd_region[i-1].end = rsvd_region[i].end;
+ --max;
+ memmove(&rsvd_region[i], &rsvd_region[i+1],
+ (max - i) * sizeof(struct rsvd_region));
+ }
+ return max;
+}
+
/*
* Request address space for all standard resources
*/
@@ -275,6 +292,7 @@
if (ret == 0 && size > 0) {
if (!base) {
sort_regions(rsvd_region, *n);
+ *n = merge_regions(rsvd_region, *n);
base = kdump_find_rsvd_region(size,
rsvd_region, *n);
}
@@ -392,6 +410,7 @@
BUG_ON(IA64_MAX_RSVD_REGIONS + 1 < n);
sort_regions(rsvd_region, num_rsvd_regions);
+ num_rsvd_regions = merge_regions(rsvd_region, num_rsvd_regions);
}
--
To unsubscribe from this list: send the line "unsubscribe linux-ia64" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
|