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[IA64] Merge overlapping reserved regions at boot 

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.

This happens because reserve_memory() blindly marks [KERNEL_START, __end]
as reserved, even though there is a free block in the middle in the kexec
case because it noticed a large gap between sections and modified the
efi_memory_map to account for this.

Signed-off-by: Petr Tesarik <ptesarik@suse.cz>
Signed-off-by: Tony Luck <tony.luck@intel.com>
This commit is contained in:
Petr Tesarik 2011-11-29 15:01:51 +01:00 committed by Tony Luck
parent 5611cc4572
commit 76d71ebddf
1 changed files with 19 additions and 0 deletions
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19
arch/ia64/kernel/setup.c
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@ -220,6 +220,23 @@ sort_regions (struct rsvd_region *rsvd_region, int max)
}
}
/* 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
*/
@ -270,6 +287,7 @@ static void __init setup_crashkernel(unsigned long total, int *n)
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);
}
@ -373,6 +391,7 @@ reserve_memory (void)
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);
}