Commit 76d71ebd authored Nov 29, 2011 by Petr Tesarik Committed by Tony Luck Dec 09, 2011

[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>

parent 5611cc45

arch/ia64/kernel/setup.c

+19 −0

Original line number	Diff line number	Diff line
		@@ -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);
		}

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