80c7842828
dlpar_online_cpu() attempts to online all threads of a core that has been added to an LPAR. If onlining a non-primary thread fails (e.g. due to an allocation failure), the core is left with at least one thread online. dlpar_cpu_add() attempts to roll back the whole operation, releasing the core back to the platform. However, since some threads of the core being removed are still online, the BUG_ON(cpu_online(cpu)) in pseries_remove_processor() strikes: LE PAGE_SIZE=64K MMU=Hash SMP NR_CPUS=2048 NUMA pSeries Modules linked in: CPU: 3 PID: 8587 Comm: drmgr Not tainted 5.3.0-rc2-00190-g9b123d1ea237-dirty #46 NIP: c0000000000eeb2c LR: c0000000000eeac4 CTR: c0000000000ee9e0 REGS: c0000001f745b6c0 TRAP: 0700 Not tainted (5.3.0-rc2-00190-g9b123d1ea237-dirty) MSR: 800000010282b033 <SF,VEC,VSX,EE,FP,ME,IR,DR,RI,LE,TM[E]> CR: 44002448 XER: 00000000 CFAR: c00000000195d718 IRQMASK: 0 GPR00: c0000000000eeac4 c0000001f745b950 c0000000032f6200 0000000000000008 GPR04: 0000000000000008 c000000003349c78 0000000000000040 00000000000001ff GPR08: 0000000000000008 0000000000000000 0000000000000001 0007ffffffffffff GPR12: 0000000084002844 c00000001ecacb80 0000000000000000 0000000000000000 GPR16: 0000000000000000 0000000000000000 0000000000000000 0000000000000000 GPR20: 0000000000000000 0000000000000000 0000000000000000 0000000000000008 GPR24: c000000003349ee0 c00000000334a2e4 c0000000fca4d7a8 c000000001d20048 GPR28: 0000000000000001 ffffffffffffffff ffffffffffffffff c0000000fca4d7c4 NIP [c0000000000eeb2c] pseries_smp_notifier+0x14c/0x2e0 LR [c0000000000eeac4] pseries_smp_notifier+0xe4/0x2e0 Call Trace: [c0000001f745b950] [c0000000000eeac4] pseries_smp_notifier+0xe4/0x2e0 (unreliable) [c0000001f745ba10] [c0000000001ac774] notifier_call_chain+0xb4/0x190 [c0000001f745bab0] [c0000000001ad62c] blocking_notifier_call_chain+0x7c/0xb0 [c0000001f745baf0] [c00000000167bda0] of_detach_node+0xc0/0x110 [c0000001f745bb50] [c0000000000e7ae4] dlpar_detach_node+0x64/0xa0 [c0000001f745bb80] [c0000000000edefc] dlpar_cpu_add+0x31c/0x360 [c0000001f745bc10] [c0000000000ee980] dlpar_cpu_probe+0x50/0xb0 [c0000001f745bc50] [c00000000002cf70] arch_cpu_probe+0x40/0x70 [c0000001f745bc70] [c000000000ccd808] cpu_probe_store+0x48/0x80 [c0000001f745bcb0] [c000000000cbcef8] dev_attr_store+0x38/0x60 [c0000001f745bcd0] [c00000000059c980] sysfs_kf_write+0x70/0xb0 [c0000001f745bd10] [c00000000059afb8] kernfs_fop_write+0xf8/0x280 [c0000001f745bd60] [c0000000004b437c] __vfs_write+0x3c/0x70 [c0000001f745bd80] [c0000000004b8710] vfs_write+0xd0/0x220 [c0000001f745bdd0] [c0000000004b8acc] ksys_write+0x7c/0x140 [c0000001f745be20] [c00000000000bbd8] system_call+0x5c/0x68 Move dlpar_offline_cpu() up in the file so that dlpar_online_cpu() can use it to re-offline any threads that have been onlined when an error is encountered. Signed-off-by: Nathan Lynch <nathanl@linux.ibm.com> Fixes: e666ae0b10aa ("powerpc/pseries: Update CPU hotplug error recovery") Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/20191016183611.10867-3-nathanl@linux.ibm.com
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.