commit bff3b04460a8 ("arm64: mm: reserve CMA and crashkernel in
ZONE_DMA32") allocates crashkernel for arm64 in the ZONE_DMA32.
However as reported by Prabhakar, this breaks kdump kernel booting in
ThunderX2 like arm64 systems. I have noticed this on another ampere
arm64 machine. The OOM log in the kdump kernel looks like this:
[ 0.240552] DMA: preallocated 128 KiB GFP_KERNEL pool for atomic allocations
[ 0.247713] swapper/0: page allocation failure: order:1, mode:0xcc1(GFP_KERNEL|GFP_DMA), nodemask=(null),cpuset=/,mems_allowed=0
<..snip..>
[ 0.274706] Call trace:
[ 0.277170] dump_backtrace+0x0/0x208
[ 0.280863] show_stack+0x1c/0x28
[ 0.284207] dump_stack+0xc4/0x10c
[ 0.287638] warn_alloc+0x104/0x170
[ 0.291156] __alloc_pages_slowpath.constprop.106+0xb08/0xb48
[ 0.296958] __alloc_pages_nodemask+0x2ac/0x2f8
[ 0.301530] alloc_page_interleave+0x20/0x90
[ 0.305839] alloc_pages_current+0xdc/0xf8
[ 0.309972] atomic_pool_expand+0x60/0x210
[ 0.314108] __dma_atomic_pool_init+0x50/0xa4
[ 0.318504] dma_atomic_pool_init+0xac/0x158
[ 0.322813] do_one_initcall+0x50/0x218
[ 0.326684] kernel_init_freeable+0x22c/0x2d0
[ 0.331083] kernel_init+0x18/0x110
[ 0.334600] ret_from_fork+0x10/0x18
This patch limits the crashkernel allocation to the first 1GB of
the RAM accessible (ZONE_DMA), as otherwise we might run into OOM
issues when crashkernel is executed, as it might have been originally
allocated from either a ZONE_DMA32 memory or mixture of memory chunks
belonging to both ZONE_DMA and ZONE_DMA32.
Fixes: bff3b04460a8 ("arm64: mm: reserve CMA and crashkernel in ZONE_DMA32")
Cc: Johannes Weiner <hannes@xxxxxxxxxxx>
Cc: Michal Hocko <mhocko@xxxxxxxxxx>
Cc: Vladimir Davydov <vdavydov.dev@xxxxxxxxx>
Cc: James Morse <james.morse@xxxxxxx>
Cc: Mark Rutland <mark.rutland@xxxxxxx>
Cc: Will Deacon <will@xxxxxxxxxx>
Cc: Catalin Marinas <catalin.marinas@xxxxxxx>
Cc: cgroups@xxxxxxxxxxxxxxx
Cc: linux-mm@xxxxxxxxx
Cc: linux-arm-kernel@xxxxxxxxxxxxxxxxxxx
Cc: linux-kernel@xxxxxxxxxxxxxxx
Cc: kexec@xxxxxxxxxxxxxxxxxxx
Reported-by: Prabhakar Kushwaha <pkushwaha@xxxxxxxxxxx>
Signed-off-by: Bhupesh Sharma <bhsharma@xxxxxxxxxx>
---
arch/arm64/mm/init.c | 16 ++++++++++++++--
1 file changed, 14 insertions(+), 2 deletions(-)
diff --git a/arch/arm64/mm/init.c b/arch/arm64/mm/init.c
index 1e93cfc7c47a..02ae4d623802 100644
--- a/arch/arm64/mm/init.c
+++ b/arch/arm64/mm/init.c
@@ -91,8 +91,15 @@ static void __init reserve_crashkernel(void)
crash_size = PAGE_ALIGN(crash_size);
if (crash_base == 0) {
- /* Current arm64 boot protocol requires 2MB alignment */
- crash_base = memblock_find_in_range(0, arm64_dma32_phys_limit,
+ /* Current arm64 boot protocol requires 2MB alignment.
+ * Also limit the crashkernel allocation to the first
+ * 1GB of the RAM accessible (ZONE_DMA), as otherwise we
+ * might run into OOM issues when crashkernel is executed,
+ * as it might have been originally allocated from
+ * either a ZONE_DMA32 memory or mixture of memory
+ * chunks belonging to both ZONE_DMA and ZONE_DMA32.
+ */
+ crash_base = memblock_find_in_range(0, arm64_dma_phys_limit,
crash_size, SZ_2M);
if (crash_base == 0) {
pr_warn("cannot allocate crashkernel (size:0x%llx)\n",
@@ -101,6 +108,11 @@ static void __init reserve_crashkernel(void)
}
} else {
/* User specifies base address explicitly. */
+ if (crash_base + crash_size > arm64_dma_phys_limit) {
+ pr_warn("cannot reserve crashkernel: region is allocatable only in ZONE_DMA range\n");
+ return;
+ }
+
if (!memblock_is_region_memory(crash_base, crash_size)) {
pr_warn("cannot reserve crashkernel: region is not memory\n");
return;
--
2.7.4
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