kernel.git/arch/powerpc/platforms/pseries, branch linux-5.3.y

powerpc/pseries: Fix cpu_hotplug_lock acquisition in resize_hpt()

2019-10-11T16:35:57Z

commit c784be435d5dae28d3b03db31753dd7a18733f0c upstream. The calls to arch_add_memory()/arch_remove_memory() are always made with the read-side cpu_hotplug_lock acquired via memory_hotplug_begin(). On pSeries, arch_add_memory()/arch_remove_memory() eventually call resize_hpt() which in turn calls stop_machine() which acquires the read-side cpu_hotplug_lock again, thereby resulting in the recursive acquisition of this lock. In the absence of CONFIG_PROVE_LOCKING, we hadn't observed a system lockup during a memory hotplug operation because cpus_read_lock() is a per-cpu rwsem read, which, in the fast-path (in the absence of the writer, which in our case is a CPU-hotplug operation) simply increments the read_count on the semaphore. Thus a recursive read in the fast-path doesn't cause any problems. However, we can hit this problem in practice if there is a concurrent CPU-Hotplug operation in progress which is waiting to acquire the write-side of the lock. This will cause the second recursive read to block until the writer finishes. While the writer is blocked since the first read holds the lock. Thus both the reader as well as the writers fail to make any progress thereby blocking both CPU-Hotplug as well as Memory Hotplug operations. Memory-Hotplug CPU-Hotplug CPU 0 CPU 1 ------ ------ 1. down_read(cpu_hotplug_lock.rw_sem) [memory_hotplug_begin] 2. down_write(cpu_hotplug_lock.rw_sem) [cpu_up/cpu_down] 3. down_read(cpu_hotplug_lock.rw_sem) [stop_machine()] Lockdep complains as follows in these code-paths. swapper/0/1 is trying to acquire lock: (____ptrval____) (cpu_hotplug_lock.rw_sem){++++}, at: stop_machine+0x2c/0x60 but task is already holding lock: (____ptrval____) (cpu_hotplug_lock.rw_sem){++++}, at: mem_hotplug_begin+0x20/0x50 other info that might help us debug this: Possible unsafe locking scenario: CPU0 ---- lock(cpu_hotplug_lock.rw_sem); lock(cpu_hotplug_lock.rw_sem); *** DEADLOCK *** May be due to missing lock nesting notation 3 locks held by swapper/0/1: #0: (____ptrval____) (&dev->mutex){....}, at: __driver_attach+0x12c/0x1b0 #1: (____ptrval____) (cpu_hotplug_lock.rw_sem){++++}, at: mem_hotplug_begin+0x20/0x50 #2: (____ptrval____) (mem_hotplug_lock.rw_sem){++++}, at: percpu_down_write+0x54/0x1a0 stack backtrace: CPU: 0 PID: 1 Comm: swapper/0 Not tainted 5.0.0-rc5-58373-gbc99402235f3-dirty #166 Call Trace: dump_stack+0xe8/0x164 (unreliable) __lock_acquire+0x1110/0x1c70 lock_acquire+0x240/0x290 cpus_read_lock+0x64/0xf0 stop_machine+0x2c/0x60 pseries_lpar_resize_hpt+0x19c/0x2c0 resize_hpt_for_hotplug+0x70/0xd0 arch_add_memory+0x58/0xfc devm_memremap_pages+0x5e8/0x8f0 pmem_attach_disk+0x764/0x830 nvdimm_bus_probe+0x118/0x240 really_probe+0x230/0x4b0 driver_probe_device+0x16c/0x1e0 __driver_attach+0x148/0x1b0 bus_for_each_dev+0x90/0x130 driver_attach+0x34/0x50 bus_add_driver+0x1a8/0x360 driver_register+0x108/0x170 __nd_driver_register+0xd0/0xf0 nd_pmem_driver_init+0x34/0x48 do_one_initcall+0x1e0/0x45c kernel_init_freeable+0x540/0x64c kernel_init+0x2c/0x160 ret_from_kernel_thread+0x5c/0x68 Fix this issue by 1) Requiring all the calls to pseries_lpar_resize_hpt() be made with cpu_hotplug_lock held. 2) In pseries_lpar_resize_hpt() invoke stop_machine_cpuslocked() as a consequence of 1) 3) To satisfy 1), in hpt_order_set(), call mmu_hash_ops.resize_hpt() with cpu_hotplug_lock held. Fixes: dbcf929c0062 ("powerpc/pseries: Add support for hash table resizing") Cc: stable@vger.kernel.org # v4.11+ Reported-by: Aneesh Kumar K.V Signed-off-by: Gautham R. Shenoy Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/1557906352-29048-1-git-send-email-ego@linux.vnet.ibm.com Signed-off-by: Greg Kroah-Hartman

powerpc/pseries: correctly track irq state in default idle

2019-10-07T17:01:23Z

[ Upstream commit 92c94dfb69e350471473fd3075c74bc68150879e ] prep_irq_for_idle() is intended to be called before entering H_CEDE (and it is used by the pseries cpuidle driver). However the default pseries idle routine does not call it, leading to mismanaged lazy irq state when the cpuidle driver isn't in use. Manifestations of this include: * Dropped IPIs in the time immediately after a cpu comes online (before it has installed the cpuidle handler), making the online operation block indefinitely waiting for the new cpu to respond. * Hitting this WARN_ON in arch_local_irq_restore(): /* * We should already be hard disabled here. We had bugs * where that wasn't the case so let's dbl check it and * warn if we are wrong. Only do that when IRQ tracing * is enabled as mfmsr() can be costly. */ if (WARN_ON_ONCE(mfmsr() & MSR_EE)) __hard_irq_disable(); Call prep_irq_for_idle() from pseries_lpar_idle() and honor its result. Fixes: 363edbe2614a ("powerpc: Default arch idle could cede processor on pseries") Signed-off-by: Nathan Lynch Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/20190910225244.25056-1-nathanl@linux.ibm.com Signed-off-by: Sasha Levin

powerpc/pseries/mobility: use cond_resched when updating device tree

2019-10-07T17:01:16Z

[ Upstream commit ccfb5bd71d3d1228090a8633800ae7cdf42a94ac ] After a partition migration, pseries_devicetree_update() processes changes to the device tree communicated from the platform to Linux. This is a relatively heavyweight operation, with multiple device tree searches, memory allocations, and conversations with partition firmware. There's a few levels of nested loops which are bounded only by decisions made by the platform, outside of Linux's control, and indeed we have seen RCU stalls on large systems while executing this call graph. Use cond_resched() in these loops so that the cpu is yielded when needed. Signed-off-by: Nathan Lynch Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/20190802192926.19277-4-nathanl@linux.ibm.com Signed-off-by: Sasha Levin

powerpc/nvdimm: Pick nearby online node if the device node is not online

2019-07-30T11:17:55Z

Currently, nvdimm subsystem expects the device numa node for SCM device to be an online node. It also doesn't try to bring the device numa node online. Hence if we use a non-online numa node as device node we hit crashes like below. This is because we try to access uninitialized NODE_DATA in different code paths. cpu 0x0: Vector: 300 (Data Access) at [c0000000fac53170] pc: c0000000004bbc50: ___slab_alloc+0x120/0xca0 lr: c0000000004bc834: __slab_alloc+0x64/0xc0 sp: c0000000fac53400 msr: 8000000002009033 dar: 73e8 dsisr: 80000 current = 0xc0000000fabb6d80 paca = 0xc000000003870000 irqmask: 0x03 irq_happened: 0x01 pid = 7, comm = kworker/u16:0 Linux version 5.2.0-06234-g76bd729b2644 (kvaneesh@ltc-boston123) (gcc version 7.4.0 (Ubuntu 7.4.0-1ubuntu1~18.04.1)) #135 SMP Thu Jul 11 05:36:30 CDT 2019 enter ? for help [link register ] c0000000004bc834 __slab_alloc+0x64/0xc0 [c0000000fac53400] c0000000fac53480 (unreliable) [c0000000fac53500] c0000000004bc818 __slab_alloc+0x48/0xc0 [c0000000fac53560] c0000000004c30a0 __kmalloc_node_track_caller+0x3c0/0x6b0 [c0000000fac535d0] c000000000cfafe4 devm_kmalloc+0x74/0xc0 [c0000000fac53600] c000000000d69434 nd_region_activate+0x144/0x560 [c0000000fac536d0] c000000000d6b19c nd_region_probe+0x17c/0x370 [c0000000fac537b0] c000000000d6349c nvdimm_bus_probe+0x10c/0x230 [c0000000fac53840] c000000000cf3cc4 really_probe+0x254/0x4e0 [c0000000fac538d0] c000000000cf429c driver_probe_device+0x16c/0x1e0 [c0000000fac53950] c000000000cf0b44 bus_for_each_drv+0x94/0x130 [c0000000fac539b0] c000000000cf392c __device_attach+0xdc/0x200 [c0000000fac53a50] c000000000cf231c bus_probe_device+0x4c/0xf0 [c0000000fac53a90] c000000000ced268 device_add+0x528/0x810 [c0000000fac53b60] c000000000d62a58 nd_async_device_register+0x28/0xa0 [c0000000fac53bd0] c0000000001ccb8c async_run_entry_fn+0xcc/0x1f0 [c0000000fac53c50] c0000000001bcd9c process_one_work+0x46c/0x860 [c0000000fac53d20] c0000000001bd4f4 worker_thread+0x364/0x5f0 [c0000000fac53db0] c0000000001c7260 kthread+0x1b0/0x1c0 [c0000000fac53e20] c00000000000b954 ret_from_kernel_thread+0x5c/0x68 The patch tries to fix this by picking the nearest online node as the SCM node. This does have a problem of us losing the information that SCM node is equidistant from two other online nodes. If applications need to understand these fine-grained details we should express then like x86 does via /sys/devices/system/node/nodeX/accessY/initiators/ With the patch we get # numactl -H available: 2 nodes (0-1) node 0 cpus: node 0 size: 0 MB node 0 free: 0 MB node 1 cpus: 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 node 1 size: 130865 MB node 1 free: 129130 MB node distances: node 0 1 0: 10 20 1: 20 10 # cat /sys/bus/nd/devices/region0/numa_node 0 # dmesg | grep papr_scm [ 91.332305] papr_scm ibm,persistent-memory:ibm,pmemory@44104001: Region registered with target node 2 and online node 0 Signed-off-by: Aneesh Kumar K.V Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/20190729095128.23707-1-aneesh.kumar@linux.ibm.com

powerpc/papr_scm: Force a scm-unbind if initial scm-bind fails

2019-07-22T13:31:00Z

In some cases initial bind of scm memory for an lpar can fail if previously it wasn't released using a scm-unbind hcall. This situation can arise due to panic of the previous kernel or forced lpar fadump. In such cases the H_SCM_BIND_MEM return a H_OVERLAP error. To mitigate such cases the patch updates papr_scm_probe() to force a call to drc_pmem_unbind() in case the initial bind of scm memory fails with EBUSY error. In case scm-bind operation again fails after the forced scm-unbind then we follow the existing error path. We also update drc_pmem_bind() to handle the H_OVERLAP error returned by phyp and indicate it as a EBUSY error back to the caller. Suggested-by: "Oliver O'Halloran" Signed-off-by: Vaibhav Jain Reviewed-by: Oliver O'Halloran Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/20190629160610.23402-4-vaibhav@linux.ibm.com

powerpc/papr_scm: Update drc_pmem_unbind() to use H_SCM_UNBIND_ALL

2019-07-22T13:31:00Z

The new hcall named H_SCM_UNBIND_ALL has been introduce that can unbind all or specific scm memory assigned to an lpar. This is more efficient than using H_SCM_UNBIND_MEM as currently we don't support partial unbind of scm memory. Hence this patch proposes following changes to drc_pmem_unbind(): * Update drc_pmem_unbind() to replace hcall H_SCM_UNBIND_MEM to H_SCM_UNBIND_ALL. * Update drc_pmem_unbind() to handles cases when PHYP asks the guest kernel to wait for specific amount of time before retrying the hcall via the 'LONG_BUSY' return value. * Ensure appropriate error code is returned back from the function in case of an error. Reviewed-by: Oliver O'Halloran Signed-off-by: Vaibhav Jain Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/20190629160610.23402-3-vaibhav@linux.ibm.com

Merge tag 'powerpc-5.3-1' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux

2019-07-13T23:08:36Z

Pull powerpc updates from Michael Ellerman: "Notable changes: - Removal of the NPU DMA code, used by the out-of-tree Nvidia driver, as well as some other functions only used by drivers that haven't (yet?) made it upstream. - A fix for a bug in our handling of hardware watchpoints (eg. perf record -e mem: ...) which could lead to register corruption and kernel crashes. - Enable HAVE_ARCH_HUGE_VMAP, which allows us to use large pages for vmalloc when using the Radix MMU. - A large but incremental rewrite of our exception handling code to use gas macros rather than multiple levels of nested CPP macros. And the usual small fixes, cleanups and improvements. Thanks to: Alastair D'Silva, Alexey Kardashevskiy, Andreas Schwab, Aneesh Kumar K.V, Anju T Sudhakar, Anton Blanchard, Arnd Bergmann, Athira Rajeev, Cédric Le Goater, Christian Lamparter, Christophe Leroy, Christophe Lombard, Christoph Hellwig, Daniel Axtens, Denis Efremov, Enrico Weigelt, Frederic Barrat, Gautham R. Shenoy, Geert Uytterhoeven, Geliang Tang, Gen Zhang, Greg Kroah-Hartman, Greg Kurz, Gustavo Romero, Krzysztof Kozlowski, Madhavan Srinivasan, Masahiro Yamada, Mathieu Malaterre, Michael Neuling, Nathan Lynch, Naveen N. Rao, Nicholas Piggin, Nishad Kamdar, Oliver O'Halloran, Qian Cai, Ravi Bangoria, Sachin Sant, Sam Bobroff, Satheesh Rajendran, Segher Boessenkool, Shaokun Zhang, Shawn Anastasio, Stewart Smith, Suraj Jitindar Singh, Thiago Jung Bauermann, YueHaibing" * tag 'powerpc-5.3-1' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux: (163 commits) powerpc/powernv/idle: Fix restore of SPRN_LDBAR for POWER9 stop state. powerpc/eeh: Handle hugepages in ioremap space ocxl: Update for AFU descriptor template version 1.1 powerpc/boot: pass CONFIG options in a simpler and more robust way powerpc/boot: add {get, put}_unaligned_be32 to xz_config.h powerpc/irq: Don't WARN continuously in arch_local_irq_restore() powerpc/module64: Use symbolic instructions names. powerpc/module32: Use symbolic instructions names. powerpc: Move PPC_HA() PPC_HI() and PPC_LO() to ppc-opcode.h powerpc/module64: Fix comment in R_PPC64_ENTRY handling powerpc/boot: Add lzo support for uImage powerpc/boot: Add lzma support for uImage powerpc/boot: don't force gzipped uImage powerpc/8xx: Add microcode patch to move SMC parameter RAM. powerpc/8xx: Use IO accessors in microcode programming. powerpc/8xx: replace #ifdefs by IS_ENABLED() in microcode.c powerpc/8xx: refactor programming of microcode CPM params. powerpc/8xx: refactor printing of microcode patch name. powerpc/8xx: Refactor microcode write powerpc/8xx: refactor writing of CPM microcode arrays ...

Merge tag 'driver-core-5.3-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core

2019-07-12T19:24:03Z

Pull driver core and debugfs updates from Greg KH: "Here is the "big" driver core and debugfs changes for 5.3-rc1 It's a lot of different patches, all across the tree due to some api changes and lots of debugfs cleanups. Other than the debugfs cleanups, in this set of changes we have: - bus iteration function cleanups - scripts/get_abi.pl tool to display and parse Documentation/ABI entries in a simple way - cleanups to Documenatation/ABI/ entries to make them parse easier due to typos and other minor things - default_attrs use for some ktype users - driver model documentation file conversions to .rst - compressed firmware file loading - deferred probe fixes All of these have been in linux-next for a while, with a bunch of merge issues that Stephen has been patient with me for" * tag 'driver-core-5.3-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core: (102 commits) debugfs: make error message a bit more verbose orangefs: fix build warning from debugfs cleanup patch ubifs: fix build warning after debugfs cleanup patch driver: core: Allow subsystems to continue deferring probe drivers: base: cacheinfo: Ensure cpu hotplug work is done before Intel RDT arch_topology: Remove error messages on out-of-memory conditions lib: notifier-error-inject: no need to check return value of debugfs_create functions swiotlb: no need to check return value of debugfs_create functions ceph: no need to check return value of debugfs_create functions sunrpc: no need to check return value of debugfs_create functions ubifs: no need to check return value of debugfs_create functions orangefs: no need to check return value of debugfs_create functions nfsd: no need to check return value of debugfs_create functions lib: 842: no need to check return value of debugfs_create functions debugfs: provide pr_fmt() macro debugfs: log errors when something goes wrong drivers: s390/cio: Fix compilation warning about const qualifiers drivers: Add generic helper to match by of_node driver_find_device: Unify the match function with class_find_device() bus_find_device: Unify the match callback with class_find_device ...

powerpc/pseries/scm: Use a specific endian format for storing uuid from the device tree

2019-07-04T14:42:10Z

We used uuid_parse to convert uuid string from device tree to two u64 components. We want to make sure we look at the uuid read from device tree in an endian-neutral fashion. For now, I am picking little-endian to be format so that we don't end up doing an additional conversion. The reason to store in a specific endian format is to enable reading the namespace created with a little-endian kernel config on a big-endian kernel. We do store the device tree uuid string as a 64-bit little-endian cookie in the label area. When booting the kernel we also compare this cookie against what is read from the device tree. For this, to work we have to store and compare these values in a CPU endian config independent fashion. Signed-off-by: Aneesh Kumar K.V Signed-off-by: Michael Ellerman

powerpc/nvdimm: Add support for multibyte read/write for metadata

2019-07-04T14:37:33Z

SCM_READ/WRITE_MEATADATA hcall supports multibyte read/write. This patch updates the metadata read/write to use 1, 2, 4 or 8 byte read/write as mentioned in PAPR document. READ/WRITE_METADATA hcall supports the 1, 2, 4, or 8 bytes read/write. For other values hcall results H_P3. Hypervisor stores the metadata contents in big-endian format and in-order to enable read/write in different granularity, we need to switch the contents to big-endian before calling HCALL. Based on an patch from Oliver O'Halloran Signed-off-by: Aneesh Kumar K.V Signed-off-by: Michael Ellerman