On Thu, 2020-06-04 at 21:26 -0500, John Donnelly wrote: > On 6/4/20 12:01 PM, Nicolas Saenz Julienne wrote: > > On Thu, 2020-06-04 at 01:17 +0530, Bhupesh Sharma wrote: > > > Hi All, > > > > > > On Wed, Jun 3, 2020 at 9:03 PM John Donnelly > > > wrote: > > > > > On Jun 3, 2020, at 8:20 AM, chenzhou wrote: > > > > > > > > > > Hi, > > > > > > > > > > > > > > > On 2020/6/3 19:47, Prabhakar Kushwaha wrote: > > > > > > Hi Chen, > > > > > > > > > > > > On Tue, Jun 2, 2020 at 8:12 PM John Donnelly < > > > > > > john.p.donnelly@oracle.com > > > > > > > wrote: > > > > > > > > > > > > > > > On Jun 2, 2020, at 12:38 AM, Prabhakar Kushwaha < > > > > > > > > prabhakar.pkin@gmail.com> wrote: > > > > > > > > > > > > > > > > On Tue, Jun 2, 2020 at 3:29 AM John Donnelly < > > > > > > > > john.p.donnelly@oracle.com> wrote: > > > > > > > > > Hi . See below ! > > > > > > > > > > > > > > > > > > > On Jun 1, 2020, at 4:02 PM, Bhupesh Sharma < > > > > > > > > > > bhsharma@redhat.com> > > > > > > > > > > wrote: > > > > > > > > > > > > > > > > > > > > Hi John, > > > > > > > > > > > > > > > > > > > > On Tue, Jun 2, 2020 at 1:01 AM John Donnelly < > > > > > > > > > > John.P.donnelly@oracle.com> 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@huawei.com> 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. > > > > > > > > > > > > > > > > > > > > > > > > > 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+0xb > > > > > > > > > > > > 10/0 > > > > > > > > > > > > xb50 > > > > > > > > > > > > [ 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. > > > > > > > > > > > > > if you consider this as valid change, can you please incorporate as > > > > > > part of your patch-set. > > > > > After commit 1a8e1cef7 ("arm64: use both ZONE_DMA and ZONE_DMA32")，the > > > > > 0- > > > > > 4G memory is splited > > > > > to DMA [mem 0x0000000000000000-0x000000003fffffff] and DMA32 [mem > > > > > 0x0000000040000000-0x00000000ffffffff] on arm64. > > > > > > > > > > From the above discussion, on your platform, the low crashkernel fall > > > > > in > > > > > DMA32 region, but your environment needs to access DMA > > > > > region, so there is the call trace. > > > > > > > > > > I have a question, why do you choose 0xc0000000 here? > > > > > > > > > > Besides, this is common code, we also need to consider about x86. > > > > > > > > > + nsaenzjulienne@suse.de > > Thanks for adding me to the conversation, and sorry for the headaches. > > > > > > Exactly . This is why it needs to be a CONFIG option for Raspberry > > > > .., or device tree option. > > > > > > > > > > > > We could revert 1a8e1cef7 since it broke Arm kdump too. > > > Well, unfortunately the patch for commit 1a8e1cef7603 ("arm64: use > > > both ZONE_DMA and ZONE_DMA32") was not Cc'ed to the kexec mailing > > > list, thus we couldn't get many eyes on it for a thorough review from > > > kexec/kdump p-o-v. > > > > > > Also we historically never had distinction in common arch code on the > > > basis of the intended end use-case: embedded, server or automotive, so > > > I am not sure introducing a Raspberry specific CONFIG option would be > > > a good idea. > > +1 > > > > From the distros perspective it's very important to keep a single kernel > > image. > > > > > So, rather than reverting the patch, we can look at addressing the > > > same properly this time - especially from a kdump p-o-v. > > > This issue has been reported by some Red Hat arm64 partners with > > > upstream kernel also and as we have noticed in the past as well, > > > hardcoding the placement of the crashkernel base address (unless the > > > base address is specified by a crashkernel=X@Y like bootargs) is also > > > not a portable suggestion. > > > > > > I am working on a possible fix and will have more updates on the same > > > in a day-or-two. > > Please keep me in the loop, we've also had issues pointing to this reported > > by > > SUSE partners. I can do some testing both on the RPi4 and on big servers > > that > > need huge crashkernel sizes. > > > > Regards, > > Nicolas > > > Hi Nicolas, > > > You want want to review this topic with the various email threads . It > has been a long journey. Will do, thanks! Regards, Nicolas