kernel.git/arch/powerpc/platforms/pseries/hotplug-memory.c, branch linux-3.15.y

powerpc/pseries: Protect remove_memory() with device hotplug lock

2014-04-28T06:32:14Z

While testing memory hot-remove, I found following dead lock: Process #1141 is drmgr, trying to remove some memory, i.e. memory499. It holds the memory_hotplug_mutex, and blocks when trying to remove file "online" under dir memory499, in kernfs_drain(), at wait_event(root->deactivate_waitq, atomic_read(&kn->active) == KN_DEACTIVATED_BIAS); Process #1120 is trying to online memory499 by echo 1 > memory499/online In .kernfs_fop_write, it uses kernfs_get_active() to increase &kn->active, thus blocking process #1141. While itself is blocked later when trying to acquire memory_hotplug_mutex, which is held by process The backtrace of both processes are shown below: [] 0xc000000001b18600 [] .__switch_to+0x144/0x200 [] .online_pages+0x74/0x7b0 [] .memory_subsys_online+0x9c/0x150 [] .device_online+0xb8/0x120 [] .online_store+0xb4/0xc0 [] .dev_attr_store+0x64/0xa0 [] .sysfs_kf_write+0x7c/0xb0 [] .kernfs_fop_write+0x154/0x1e0 [] .vfs_write+0xe0/0x260 [] .SyS_write+0x64/0x110 [] syscall_exit+0x0/0x7c [] 0xc000000001b18600 [] .__switch_to+0x144/0x200 [] .__kernfs_remove+0x204/0x300 [] .kernfs_remove_by_name_ns+0x68/0xf0 [] .sysfs_remove_file_ns+0x38/0x60 [] .device_remove_attrs+0x54/0xc0 [] .device_del+0x158/0x250 [] .device_unregister+0x34/0xa0 [] .unregister_memory_section+0x164/0x170 [] .__remove_pages+0x108/0x4c0 [] .arch_remove_memory+0x60/0xc0 [] .remove_memory+0x8c/0xe0 [] .pseries_remove_memblock+0xd4/0x160 [] .pseries_memory_notifier+0x27c/0x290 [] .notifier_call_chain+0x8c/0x100 [] .__blocking_notifier_call_chain+0x6c/0xe0 [] .of_property_notify+0x7c/0xc0 [] .of_update_property+0x3c/0x1b0 [] .ofdt_write+0x3dc/0x740 [] .proc_reg_write+0xac/0x110 [] .vfs_write+0xe0/0x260 [] .SyS_write+0x64/0x110 [] syscall_exit+0x0/0x7c This patch uses lock_device_hotplug() to protect remove_memory() called in pseries_remove_memblock(), which is also stated before function remove_memory(): * NOTE: The caller must call lock_device_hotplug() to serialize hotplug * and online/offline operations before this call, as required by * try_offline_node(). */ void __ref remove_memory(int nid, u64 start, u64 size) With this lock held, the other process(#1120 above) trying to online the memory block will retry the system call when calling lock_device_hotplug_sysfs(), and finally find No such device error. Signed-off-by: Li Zhong Signed-off-by: Benjamin Herrenschmidt

powerpc/pseries: Use remove_memory() to remove memory

2014-03-07T04:53:13Z

The memory remove code for powerpc/pseries should call remove_memory() so that we are holding the hotplug_memory lock during memory remove operations. This patch updates the memory node remove handler to call remove_memory() and adds a ppc_md.remove_memory() entry to handle pseries specific work that is called from arch_remove_memory(). During memory remove in pseries_remove_memblock() we have to stay with removing memory one section at a time. This is needed because of how memory resources are handled. During memory add for pseries (via the probe file in sysfs) we add memory one section at a time which gives us a memory resource for each section. Future patches will aim to address this so will not have to remove memory one section at a time. Signed-off-by: Nathan Fontenot Signed-off-by: Benjamin Herrenschmidt

powerpc: add explicit OF includes

2013-10-10T01:04:11Z

When removing prom.h include by of.h, several OF headers will no longer be implicitly included. Add explicit includes of of_*.h as needed. Signed-off-by: Rob Herring Acked-by: Grant Likely Cc: Benjamin Herrenschmidt Cc: Paul Mackerras Cc: Anatolij Gustschin Cc: Kumar Gala Cc: Olof Johansson Cc: linuxppc-dev@lists.ozlabs.org

mm, hotplug: avoid compiling memory hotremove functions when disabled

2013-04-29T22:54:37Z

__remove_pages() is only necessary for CONFIG_MEMORY_HOTREMOVE. PowerPC pseries will return -EOPNOTSUPP if unsupported. Adding an #ifdef causes several other functions it depends on to also become unnecessary, which saves in .text when disabled (it's disabled in most defconfigs besides powerpc, including x86). remove_memory_block() becomes static since it is not referenced outside of drivers/base/memory.c. Build tested on x86 and powerpc with CONFIG_MEMORY_HOTREMOVE both enabled and disabled. Signed-off-by: David Rientjes Acked-by: Toshi Kani Cc: Benjamin Herrenschmidt Cc: Paul Mackerras Cc: Greg Kroah-Hartman Cc: Wen Congyang Cc: Tang Chen Cc: Yasuaki Ishimatsu Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

powerpc+of: Add of node/property notification chain for adds and removes

2012-11-15T01:56:41Z

This patch moves the notification chain for updates to the device tree from the powerpc/pseries code to the base OF code. This makes this functionality available to all architectures. Additionally the notification chain is updated to allow notifications for property add/remove/update. To make this work a pointer to a new struct (of_prop_reconfig) is passed to the routines in the notification chain. The of_prop_reconfig property contains a pointer to the node containing the property and a pointer to the property itself. In the case of property updates, the property pointer refers to the new property. Signed-off-by: Nathan Fontenot Acked-by: Rob Herring Acked-by: Grant Likely Signed-off-by: Benjamin Herrenschmidt

arch/powerpc/platforms/pseries/hotplug-memory.c: section removal cleanups

2012-10-10T23:50:14Z

Followups to d760afd4d257 ("memory-hotplug: suppress "Trying to free nonexistent resource " warning"). - use unsigned long type, as overflows are conceivable - rename `i' to the less-misleading and more informative `section' Cc: Benjamin Herrenschmidt Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

arch/powerpc/platforms/pseries/hotplug-memory.c: fix section handling code

2012-10-10T23:50:13Z

Fix arch/powerpc/platforms/pseries/hotplug-memory.c: In function 'pseries_remove_memblock': arch/powerpc/platforms/pseries/hotplug-memory.c:103:17: error: unused variable 'pfn' [-Werror=unused-variable] Caused by commit d760afd4d257 ("memory-hotplug: suppress "Trying to free nonexistent resource " warning"). Reported-by: Stephen Rothwell Cc: Yasuaki Ishimatsu Tested-by: Stephen Rothwell Signed-off-by: Andrew Morton Tested-by: Nathan Fontenot Tested-by: Benjamin Herrenschmidt Signed-off-by: Linus Torvalds

memory-hotplug: suppress "Trying to free nonexistent resource " warning

2012-10-09T07:23:04Z

When our x86 box calls __remove_pages(), release_mem_region() shows many warnings. And x86 box cannot unregister iomem_resource. "Trying to free nonexistent resource " release_mem_region() has been changed to be called in each PAGES_PER_SECTION by commit de7f0cba9678 ("memory hotplug: release memory regions in PAGES_PER_SECTION chunks"). Because powerpc registers iomem_resource in each PAGES_PER_SECTION chunk. But when I hot add memory on x86 box, iomem_resource is register in each _CRS not PAGES_PER_SECTION chunk. So x86 box unregisters iomem_resource. The patch fixes the problem. Signed-off-by: Yasuaki Ishimatsu Cc: David Rientjes Cc: Jiang Liu Cc: Len Brown Cc: Benjamin Herrenschmidt Cc: Paul Mackerras Cc: Christoph Lameter Cc: Minchan Kim Cc: Andrew Morton Cc: KOSAKI Motohiro Cc: Wen Congyang Cc: Dave Hansen Cc: Nathan Fontenot Cc: Badari Pulavarty Cc: Yasunori Goto Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

Merge branch 'next' of git://git.kernel.org/pub/scm/linux/kernel/git/benh/powerpc

2011-07-26T05:59:39Z

* 'next' of git://git.kernel.org/pub/scm/linux/kernel/git/benh/powerpc: (99 commits) drivers/virt: add missing linux/interrupt.h to fsl_hypervisor.c powerpc/85xx: fix mpic configuration in CAMP mode powerpc: Copy back TIF flags on return from softirq stack powerpc/64: Make server perfmon only built on ppc64 server devices powerpc/pseries: Fix hvc_vio.c build due to recent changes powerpc: Exporting boot_cpuid_phys powerpc: Add CFAR to oops output hvc_console: Add kdb support powerpc/pseries: Fix hvterm_raw_get_chars to accept < 16 chars, fixing xmon powerpc/irq: Quieten irq mapping printks powerpc: Enable lockup and hung task detectors in pseries and ppc64 defeconfigs powerpc: Add mpt2sas driver to pseries and ppc64 defconfig powerpc: Disable IRQs off tracer in ppc64 defconfig powerpc: Sync pseries and ppc64 defconfigs powerpc/pseries/hvconsole: Fix dropped console output hvc_console: Improve tty/console put_chars handling powerpc/kdump: Fix timeout in crash_kexec_wait_realmode powerpc/mm: Fix output of total_ram. powerpc/cpufreq: Add cpufreq driver for Momentum Maple boards powerpc: Correct annotations of pmu registration functions ... Fix up trivial Kconfig/Makefile conflicts in arch/powerpc, drivers, and drivers/cpufreq

powerpc/mm: Fix memory_block_size_bytes() for non-pseries

2011-07-12T01:16:45Z

Just compiling pseries in the kernel causes it to override memory_block_size_bytes() regardless of what is the runtime platform. This cleans up the implementation of that function, fixing a bug or two while at it, so that it's harmless (and potentially useful) for other platforms. Without this, bugs in that code would trigger a WARN_ON() in drivers/base/memory.c when booting some different platforms. If/when we have another platform supporting memory hotplug we might want to either move that out to a generic place or make it a ppc_md. callback. Signed-off-by: Benjamin Herrenschmidt