> On Jun 2, 2020, at 12:38 AM, Prabhakar Kushwaha <prabhakar.pkin@xxxxxxxxx> wrote: > > On Tue, Jun 2, 2020 at 3:29 AM John Donnelly <john.p.donnelly@xxxxxxxxxx> wrote: >> >> Hi . See below ! >> >>> On Jun 1, 2020, at 4:02 PM, Bhupesh Sharma <bhsharma@xxxxxxxxxx> wrote: >>> >>> Hi John, >>> >>> On Tue, Jun 2, 2020 at 1:01 AM John Donnelly <John.P.donnelly@xxxxxxxxxx> wrote: >>>> >>>> Hi, >>>> >>>> >>>> On 6/1/20 7:02 AM, Prabhakar Kushwaha wrote: >>>>> Hi Chen, >>>>> >>>>> On Thu, May 21, 2020 at 3:05 PM Chen Zhou <chenzhou10@xxxxxxxxxx> wrote: >>>>>> This patch series enable reserving crashkernel above 4G in arm64. >>>>>> >>>>>> There are following issues in arm64 kdump: >>>>>> 1. We use crashkernel=X to reserve crashkernel below 4G, which will fail >>>>>> when there is no enough low memory. >>>>>> 2. Currently, crashkernel=Y@X can be used to reserve crashkernel above 4G, >>>>>> in this case, if swiotlb or DMA buffers are required, crash dump kernel >>>>>> will boot failure because there is no low memory available for allocation. >>>>>> >>>>>> To solve these issues, introduce crashkernel=X,low to reserve specified >>>>>> size low memory. >>>>>> Crashkernel=X tries to reserve memory for the crash dump kernel under >>>>>> 4G. If crashkernel=Y,low is specified simultaneously, reserve spcified >>>>>> size low memory for crash kdump kernel devices firstly and then reserve >>>>>> memory above 4G. >>>>>> >>>>>> When crashkernel is reserved above 4G in memory, that is, crashkernel=X,low >>>>>> is specified simultaneously, kernel should reserve specified size low memory >>>>>> for crash dump kernel devices. So there may be two crash kernel regions, one >>>>>> is below 4G, the other is above 4G. >>>>>> In order to distinct from the high region and make no effect to the use of >>>>>> kexec-tools, rename the low region as "Crash kernel (low)", and add DT property >>>>>> "linux,low-memory-range" to crash dump kernel's dtb to pass the low region. >>>>>> >>>>>> Besides, we need to modify kexec-tools: >>>>>> arm64: kdump: add another DT property to crash dump kernel's dtb(see [1]) >>>>>> >>>>>> The previous changes and discussions can be retrieved from: >>>>>> >>>>>> Changes since [v7] >>>>>> - Move x86 CRASH_ALIGN to 2M >>>>>> Suggested by Dave and do some test, move x86 CRASH_ALIGN to 2M. >>>>>> - Update Documentation/devicetree/bindings/chosen.txt >>>>>> Add corresponding documentation to Documentation/devicetree/bindings/chosen.txt suggested by Arnd. >>>>>> - Add Tested-by from Jhon and pk >>>>>> >>>>>> Changes since [v6] >>>>>> - Fix build errors reported by kbuild test robot. >>>>>> >>>>>> Changes since [v5] >>>>>> - Move reserve_crashkernel_low() into kernel/crash_core.c. >>>>>> - Delete crashkernel=X,high. >>>>>> - Modify crashkernel=X,low. >>>>>> If crashkernel=X,low is specified simultaneously, reserve spcified size low >>>>>> memory for crash kdump kernel devices firstly and then reserve memory above 4G. >>>>>> In addition, rename crashk_low_res as "Crash kernel (low)" for arm64, and then >>>>>> pass to crash dump kernel by DT property "linux,low-memory-range". >>>>>> - Update Documentation/admin-guide/kdump/kdump.rst. >>>>>> >>>>>> Changes since [v4] >>>>>> - Reimplement memblock_cap_memory_ranges for multiple ranges by Mike. >>>>>> >>>>>> Changes since [v3] >>>>>> - Add memblock_cap_memory_ranges back for multiple ranges. >>>>>> - Fix some compiling warnings. >>>>>> >>>>>> Changes since [v2] >>>>>> - Split patch "arm64: kdump: support reserving crashkernel above 4G" as >>>>>> two. Put "move reserve_crashkernel_low() into kexec_core.c" in a separate >>>>>> patch. >>>>>> >>>>>> Changes since [v1]: >>>>>> - Move common reserve_crashkernel_low() code into kernel/kexec_core.c. >>>>>> - Remove memblock_cap_memory_ranges() i added in v1 and implement that >>>>>> in fdt_enforce_memory_region(). >>>>>> There are at most two crash kernel regions, for two crash kernel regions >>>>>> case, we cap the memory range [min(regs[*].start), max(regs[*].end)] >>>>>> and then remove the memory range in the middle. >>>>>> >>>>>> [1]: https://urldefense.com/v3/__http://lists.infradead.org/pipermail/kexec/2020-May/025128.html__;!!GqivPVa7Brio!LnTSARkCt0V0FozR0KmqooaH5ADtdXvs3mPdP3KRVqALmvSK2VmCkIPIhsaxbvpn1uM1$ >>>>>> [v1]: https://urldefense.com/v3/__https://lkml.org/lkml/2019/4/2/1174__;!!GqivPVa7Brio!LnTSARkCt0V0FozR0KmqooaH5ADtdXvs3mPdP3KRVqALmvSK2VmCkIPIhsaxbt0xN9PE$ >>>>>> [v2]: https://urldefense.com/v3/__https://lkml.org/lkml/2019/4/9/86__;!!GqivPVa7Brio!LnTSARkCt0V0FozR0KmqooaH5ADtdXvs3mPdP3KRVqALmvSK2VmCkIPIhsaxbub7yUQH$ >>>>>> [v3]: https://urldefense.com/v3/__https://lkml.org/lkml/2019/4/9/306__;!!GqivPVa7Brio!LnTSARkCt0V0FozR0KmqooaH5ADtdXvs3mPdP3KRVqALmvSK2VmCkIPIhsaxbnc4zPPV$ >>>>>> [v4]: https://urldefense.com/v3/__https://lkml.org/lkml/2019/4/15/273__;!!GqivPVa7Brio!LnTSARkCt0V0FozR0KmqooaH5ADtdXvs3mPdP3KRVqALmvSK2VmCkIPIhsaxbvsAsZLu$ >>>>>> [v5]: https://urldefense.com/v3/__https://lkml.org/lkml/2019/5/6/1360__;!!GqivPVa7Brio!LnTSARkCt0V0FozR0KmqooaH5ADtdXvs3mPdP3KRVqALmvSK2VmCkIPIhsaxbl24n-79$ >>>>>> [v6]: https://urldefense.com/v3/__https://lkml.org/lkml/2019/8/30/142__;!!GqivPVa7Brio!LnTSARkCt0V0FozR0KmqooaH5ADtdXvs3mPdP3KRVqALmvSK2VmCkIPIhsaxbs7r8G2a$ >>>>>> [v7]: https://urldefense.com/v3/__https://lkml.org/lkml/2019/12/23/411__;!!GqivPVa7Brio!LnTSARkCt0V0FozR0KmqooaH5ADtdXvs3mPdP3KRVqALmvSK2VmCkIPIhsaxbiFUH90G$ >>>>>> >>>>>> Chen Zhou (5): >>>>>> x86: kdump: move reserve_crashkernel_low() into crash_core.c >>>>>> arm64: kdump: reserve crashkenel above 4G for crash dump kernel >>>>>> arm64: kdump: add memory for devices by DT property, low-memory-range >>>>>> kdump: update Documentation about crashkernel on arm64 >>>>>> dt-bindings: chosen: Document linux,low-memory-range for arm64 kdump >>>>>> >>>>> We are getting "warn_alloc" [1] warning during boot of kdump kernel >>>>> with bootargs as [2] of primary kernel. >>>>> This error observed on ThunderX2 ARM64 platform. >>>>> >>>>> It is observed with latest upstream tag (v5.7-rc3) with this patch set >>>>> and https://urldefense.com/v3/__https://lists.infradead.org/pipermail/kexec/2020-May/025128.html__;!!GqivPVa7Brio!LnTSARkCt0V0FozR0KmqooaH5ADtdXvs3mPdP3KRVqALmvSK2VmCkIPIhsaxbiIAAlzu$ >>>>> Also **without** this patch-set >>>>> "https://urldefense.com/v3/__https://www.spinics.net/lists/arm-kernel/msg806882.html__;!!GqivPVa7Brio!LnTSARkCt0V0FozR0KmqooaH5ADtdXvs3mPdP3KRVqALmvSK2VmCkIPIhsaxbjC6ujMA$"; >>>>> >>>>> This issue comes whenever crashkernel memory is reserved after 0xc000_0000. >>>>> More details discussed earlier in >>>>> https://urldefense.com/v3/__https://www.spinics.net/lists/arm-kernel/msg806882.html__;!!GqivPVa7Brio!LnTSARkCt0V0FozR0KmqooaH5ADtdXvs3mPdP3KRVqALmvSK2VmCkIPIhsaxbjC6ujMA$ without any >>>>> solution >>>>> >>>>> This patch-set is expected to solve similar kind of issue. >>>>> i.e. low memory is only targeted for DMA, swiotlb; So above mentioned >>>>> observation should be considered/fixed. . >>>>> >>>>> --pk >>>>> >>>>> [1] >>>>> [ 30.366695] DMI: Cavium Inc. Saber/Saber, BIOS >>>>> TX2-FW-Release-3.1-build_01-2803-g74253a541a mm/dd/yyyy >>>>> [ 30.367696] NET: Registered protocol family 16 >>>>> [ 30.369973] swapper/0: page allocation failure: order:6, >>>>> mode:0x1(GFP_DMA), nodemask=(null),cpuset=/,mems_allowed=0 >>>>> [ 30.369980] CPU: 0 PID: 1 Comm: swapper/0 Not tainted 5.7.0-rc3+ #121 >>>>> [ 30.369981] Hardware name: Cavium Inc. Saber/Saber, BIOS >>>>> TX2-FW-Release-3.1-build_01-2803-g74253a541a mm/dd/yyyy >>>>> [ 30.369984] Call trace: >>>>> [ 30.369989] dump_backtrace+0x0/0x1f8 >>>>> [ 30.369991] show_stack+0x20/0x30 >>>>> [ 30.369997] dump_stack+0xc0/0x10c >>>>> [ 30.370001] warn_alloc+0x10c/0x178 >>>>> [ 30.370004] __alloc_pages_slowpath.constprop.111+0xb10/0xb50 >>>>> [ 30.370006] __alloc_pages_nodemask+0x2b4/0x300 >>>>> [ 30.370008] alloc_page_interleave+0x24/0x98 >>>>> [ 30.370011] alloc_pages_current+0xe4/0x108 >>>>> [ 30.370017] dma_atomic_pool_init+0x44/0x1a4 >>>>> [ 30.370020] do_one_initcall+0x54/0x228 >>>>> [ 30.370027] kernel_init_freeable+0x228/0x2cc >>>>> [ 30.370031] kernel_init+0x1c/0x110 >>>>> [ 30.370034] ret_from_fork+0x10/0x18 >>>>> [ 30.370036] Mem-Info: >>>>> [ 30.370064] active_anon:0 inactive_anon:0 isolated_anon:0 >>>>> [ 30.370064] active_file:0 inactive_file:0 isolated_file:0 >>>>> [ 30.370064] unevictable:0 dirty:0 writeback:0 unstable:0 >>>>> [ 30.370064] slab_reclaimable:34 slab_unreclaimable:4438 >>>>> [ 30.370064] mapped:0 shmem:0 pagetables:14 bounce:0 >>>>> [ 30.370064] free:1537719 free_pcp:219 free_cma:0 >>>>> [ 30.370070] Node 0 active_anon:0kB inactive_anon:0kB >>>>> active_file:0kB inactive_file:0kB unevictable:0kB isolated(anon):0kB >>>>> isolated(file):0kB mapped:0kB dirty:0kB writeback:0kB shmem:0kB >>>>> shmem_thp: 0kB shmem_pmdmapped: 0kB anon_thp: 0kB writeback_tmp:0kB >>>>> unstable:0kB all_unreclaimable? no >>>>> [ 30.370073] Node 1 active_anon:0kB inactive_anon:0kB >>>>> active_file:0kB inactive_file:0kB unevictable:0kB isolated(anon):0kB >>>>> isolated(file):0kB mapped:0kB dirty:0kB writeback:0kB shmem:0kB >>>>> shmem_thp: 0kB shmem_pmdmapped: 0kB anon_thp: 0kB writeback_tmp:0kB >>>>> unstable:0kB all_unreclaimable? no >>>>> [ 30.370079] Node 0 DMA free:0kB min:0kB low:0kB high:0kB >>>>> reserved_highatomic:0KB active_anon:0kB inactive_anon:0kB >>>>> active_file:0kB inactive_file:0kB unevictable:0kB writepending:0kB >>>>> present:128kB managed:0kB mlocked:0kB kernel_stack:0kB pagetables:0kB >>>>> bounce:0kB free_pcp:0kB local_pcp:0kB free_cma:0kB >>>>> [ 30.370084] lowmem_reserve[]: 0 250 6063 6063 >>>>> [ 30.370090] Node 0 DMA32 free:256000kB min:408kB low:664kB >>>>> high:920kB reserved_highatomic:0KB active_anon:0kB inactive_anon:0kB >>>>> active_file:0kB inactive_file:0kB unevictable:0kB writepending:0kB >>>>> present:269700kB managed:256000kB mlocked:0kB kernel_stack:0kB >>>>> pagetables:0kB bounce:0kB free_pcp:0kB local_pcp:0kB free_cma:0kB >>>>> [ 30.370094] lowmem_reserve[]: 0 0 5813 5813 >>>>> [ 30.370100] Node 0 Normal free:5894876kB min:9552kB low:15504kB >>>>> high:21456kB reserved_highatomic:0KB active_anon:0kB inactive_anon:0kB >>>>> active_file:0kB inactive_file:0kB unevictable:0kB writepending:0kB >>>>> present:8388608kB managed:5953112kB mlocked:0kB kernel_stack:21672kB >>>>> pagetables:56kB bounce:0kB free_pcp:876kB local_pcp:176kB free_cma:0kB >>>>> [ 30.370104] lowmem_reserve[]: 0 0 0 0 >>>>> [ 30.370107] Node 0 DMA: 0*4kB 0*8kB 0*16kB 0*32kB 0*64kB 0*128kB >>>>> 0*256kB 0*512kB 0*1024kB 0*2048kB 0*4096kB = 0kB >>>>> [ 30.370113] Node 0 DMA32: 0*4kB 0*8kB 0*16kB 0*32kB 0*64kB 0*128kB >>>>> 0*256kB 0*512kB 0*1024kB 1*2048kB (M) 62*4096kB (M) = 256000kB >>>>> [ 30.370119] Node 0 Normal: 2*4kB (M) 3*8kB (ME) 2*16kB (UE) 3*32kB >>>>> (UM) 1*64kB (U) 2*128kB (M) 2*256kB (ME) 3*512kB (ME) 3*1024kB (ME) >>>>> 3*2048kB (UME) 1436*4096kB (M) = 5893600kB >>>>> [ 30.370129] Node 0 hugepages_total=0 hugepages_free=0 >>>>> hugepages_surp=0 hugepages_size=1048576kB >>>>> [ 30.370130] 0 total pagecache pages >>>>> [ 30.370132] 0 pages in swap cache >>>>> [ 30.370134] Swap cache stats: add 0, delete 0, find 0/0 >>>>> [ 30.370135] Free swap = 0kB >>>>> [ 30.370136] Total swap = 0kB >>>>> [ 30.370137] 2164609 pages RAM >>>>> [ 30.370139] 0 pages HighMem/MovableOnly >>>>> [ 30.370140] 612331 pages reserved >>>>> [ 30.370141] 0 pages hwpoisoned >>>>> [ 30.370143] DMA: failed to allocate 256 KiB pool for atomic >>>>> coherent allocation >>>> >>>> >>>> During my testing I saw the same error and Chen's solution corrected it . >>> >>> Which combination you are using on your side? I am using Prabhakar's >>> suggested environment and can reproduce the issue >>> with or without Chen's crashkernel support above 4G patchset. >>> >>> I am also using a ThunderX2 platform with latest makedumpfile code and >>> kexec-tools (with the suggested patch >>> <https://urldefense.com/v3/__https://lists.infradead.org/pipermail/kexec/2020-May/025128.html__;!!GqivPVa7Brio!J6lUig58-Gw6TKZnEEYzEeSU36T-1SqlB1kImU00xtX_lss5Tx-JbUmLE9TJC3foXBLg$ >). >>> >>> Thanks, >>> Bhupesh >> >> >> I did this activity 5 months ago and I have moved on to other activities. My DMA failures were related to PCI devices that could not be enumerated because low-DMA space was not available when crashkernel was moved above 4G; I don’t recall the exact platform. >> >> >> >> For this failure , >> >>>>> DMA: failed to allocate 256 KiB pool for atomic >>>>> coherent allocation >> >> >> Is due to : >> >> >> 3618082c >> ("arm64 use both ZONE_DMA and ZONE_DMA32") >> >> With the introduction of ZONE_DMA to support the Raspberry DMA >> region below 1G, the crashkernel is placed in the upper 4G >> ZONE_DMA_32 region. Since the crashkernel does not have access >> to the ZONE_DMA region, it prints out call trace during bootup. >> >> It is due to having this CONFIG item ON : >> >> >> CONFIG_ZONE_DMA=y >> >> Turning off ZONE_DMA fixes a issue and Raspberry PI 4 will >> use the device tree to specify memory below 1G. >> >> > > Disabling ZONE_DMA is temporary solution. We may need proper solution Perhaps the Raspberry platform configuration dependencies need separated from “server class” Arm equipment ? Or auto-configured on boot ? Consult an expert ;-) > >> I would like to see Chen’s feature added , perhaps as EXPERIMENTAL, so we can get some configuration testing done on it. It corrects having a DMA zone in low memory while crash-kernel is above 4GB. This has been going on for a year now. > > I will also like this patch to be added in Linux as early as possible. > > Issue mentioned by me happens with or without this patch. > > This patch-set can consider fixing because it uses low memory for DMA > & swiotlb only. > We can consider restricting crashkernel within the required range like below > > diff --git a/kernel/crash_core.c b/kernel/crash_core.c > index 7f9e5a6dc48c..bd67b90d35bd 100644 > --- a/kernel/crash_core.c > +++ b/kernel/crash_core.c > @@ -354,7 +354,7 @@ int __init reserve_crashkernel_low(void) > return 0; > } > > - low_base = memblock_find_in_range(0, 1ULL << 32, low_size, CRASH_ALIGN); > + low_base = memblock_find_in_range(0,0xc0000000, low_size, CRASH_ALIGN); > if (!low_base) { > pr_err("Cannot reserve %ldMB crashkernel low memory, > please try smaller size.\n", > (unsigned long)(low_size >> 20)); > > I suspect 0xc0000000 would need to be a CONFIG item and not hard-coded. > Similar change can be considered for scenario "without" this patch. > But it will decrease memory availability for crashkernel. > Hence increase the failure probability of crashkernel reservation. > > --pk
