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. 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. Thank you, John. ( Note .. I am not on the all the kernel-dlist emails so this won’t be seen by everyone , - someone may have to bounce it )
