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 > 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)); 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
