On 09/27/2010 05:53 PM, Vivek Goyal wrote:
> Actually, hardcoding the upper limit to 4G is probably not the best idea.
> Kexec loads the the relocatable binary (purgatory) and I remember that
> one of the generated relocation type was signed 32 bit and allowed max value
> to be 2G only. So IIRC, purgatory code always needed to be loaded below 2G.
also kexec want bzImage under 37ffffff.
>
> I liked HPA's other idea better of introducing
> memblock_find_in_range_lowest()
> so that we search bottom up and not rely on a specific upper limit.
>
Please check.
[PATCH -v4] x86, memblock: Fix crashkernel allocation
Cai Qian found crashkernel is broken with x86 memblock changes
1. crashkernel=1...@32m always reported that range is used, even first kernel
is small
no one use that range
2. always get following report when using "kexec -p"
Could not find a free area of memory of a000 bytes...
locate_hole failed
The root cause is that generic memblock_find_in_range() will try to get range
from top_down.
But crashkernel do need from low and specified range.
Let's limit the target range with rash_base + crash_size to make sure that
We get range from bottom.
-v4: add find_memblock_find_in_range_lowest() according to hpa and vivik.
Reported-and-Bisected-by: CAI Qian <caiq...@redhat.com>
Signed-off-by: Yinghai Lu <ying...@kernel.org>
---
arch/x86/include/asm/memblock.h | 2 +
arch/x86/kernel/setup.c | 8 +++---
arch/x86/mm/memblock.c | 52 ++++++++++++++++++++++++++++++++++++++++
3 files changed, 58 insertions(+), 4 deletions(-)
Index: linux-2.6/arch/x86/mm/memblock.c
===================================================================
--- linux-2.6.orig/arch/x86/mm/memblock.c
+++ linux-2.6/arch/x86/mm/memblock.c
@@ -352,3 +352,55 @@ u64 __init memblock_x86_hole_size(u64 st
return end - start - ((u64)ram << PAGE_SHIFT);
}
+
+/* Check for already reserved areas */
+static inline bool __init check_with_memblock_reserved(u64 *addrp, u64 size,
u64 align)
+{
+ u64 addr = *addrp;
+ bool changed = false;
+ struct memblock_region *r;
+again:
+ for_each_memblock(reserved, r) {
+ if ((addr + size) > r->base && addr < (r->base + r->size)) {
+ addr = round_up(r->base + r->size, align);
+ changed = true;
+ goto again;
+ }
+ }
+
+ if (changed)
+ *addrp = addr;
+
+ return changed;
+}
+
+/*
+ * Find a free area with specified alignment in a specific range from bottom up
+ */
+u64 __init memblock_find_in_range_lowest(u64 start, u64 end, u64 size, u64
align)
+{
+ struct memblock_region *r;
+
+ for_each_memblock(memory, r) {
+ u64 ei_start = r->base;
+ u64 ei_last = ei_start + r->size;
+ u64 addr, last;
+
+ addr = round_up(ei_start, align);
+ if (addr < start)
+ addr = round_up(start, align);
+ if (addr >= ei_last)
+ continue;
+ while (check_with_memblock_reserved(&addr, size, align) &&
addr+size <= ei_last)
+ ;
+ last = addr + size;
+ if (last > ei_last)
+ continue;
+ if (last > end)
+ continue;
+
+ return addr;
+ }
+
+ return MEMBLOCK_ERROR;
+}
Index: linux-2.6/arch/x86/include/asm/memblock.h
===================================================================
--- linux-2.6.orig/arch/x86/include/asm/memblock.h
+++ linux-2.6/arch/x86/include/asm/memblock.h
@@ -18,4 +18,6 @@ u64 memblock_x86_find_in_range_node(int
u64 memblock_x86_free_memory_in_range(u64 addr, u64 limit);
u64 memblock_x86_memory_in_range(u64 addr, u64 limit);
+u64 memblock_find_in_range_lowest(u64 start, u64 end, u64 size, u64 align);
+
#endif
Index: linux-2.6/arch/x86/kernel/setup.c
===================================================================
--- linux-2.6.orig/arch/x86/kernel/setup.c
+++ linux-2.6/arch/x86/kernel/setup.c
@@ -518,8 +518,8 @@ static void __init reserve_crashkernel(v
if (crash_base <= 0) {
const unsigned long long alignment = 16<<20; /* 16M */
- crash_base = memblock_find_in_range(alignment, ULONG_MAX,
crash_size,
- alignment);
+ crash_base = memblock_find_in_range_lowest(alignment,
+ ULONG_MAX, crash_size, alignment);
if (crash_base == MEMBLOCK_ERROR) {
pr_info("crashkernel reservation failed - No suitable
area found.\n");
return;
@@ -527,8 +527,8 @@ static void __init reserve_crashkernel(v
} else {
unsigned long long start;
- start = memblock_find_in_range(crash_base, ULONG_MAX,
crash_size,
- 1<<20);
+ start = memblock_find_in_range(crash_base,
+ crash_base + crash_size, crash_size, 1<<20);
if (start != crash_base) {
pr_info("crashkernel reservation failed - memory is in
use.\n");
return;
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