On Monday, May 20, 2013 01:55:33 PM Toshi Kani wrote: > On Mon, 2013-05-20 at 21:47 +0200, Rafael J. Wysocki wrote: > > On Monday, May 20, 2013 11:27:56 AM Toshi Kani wrote: > > > On Sun, 2013-05-19 at 01:34 +0200, Rafael J. Wysocki wrote: > > > > From: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx> > > : > > > > > - lock_memory_hotplug(); > > > > - > > > > - /* > > > > - * we have offlined all memory blocks like this: > > > > - * 1. lock memory hotplug > > > > - * 2. offline a memory block > > > > - * 3. unlock memory hotplug > > > > - * > > > > - * repeat step1-3 to offline the memory block. All memory blocks > > > > - * must be offlined before removing memory. But we don't hold the > > > > - * lock in the whole operation. So we should check whether all > > > > - * memory blocks are offlined. > > > > - */ > > > > - > > > > - ret = walk_memory_range(start_pfn, end_pfn, NULL, > > > > - is_memblock_offlined_cb); > > > > - if (ret) { > > > > - unlock_memory_hotplug(); > > > > - return ret; > > > > - } > > > > - > > > > > > I think the above procedure is still useful for safe guard. > > > > But then it shoud to BUG_ON() instead of returning an error (which isn't very > > useful for anything now). > > Right since we cannot fail at that state. > > > > > - /* remove memmap entry */ > > > > - firmware_map_remove(start, start + size, "System RAM"); > > > > - > > > > - arch_remove_memory(start, size); > > > > - > > > > - try_offline_node(nid); > > > > > > The above procedure performs memory hot-delete specific operations and > > > is necessary. > > > > OK, I see. I'll replace this patch with something simpler, then. > > Thanks. The replacement patch is appended. Thanks, Rafael --- From: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx> Subject: Memory hotplug / ACPI: Simplify memory removal Now that the memory offlining should be taken care of by the companion device offlining code in acpi_scan_hot_remove(), the ACPI memory hotplug driver doesn't need to offline it in remove_memory() any more. Moreover, since the return value of remove_memory() is not used, it's better to make it be a void function and trigger a BUG() if the memory scheduled for removal is not offline. Change the code in accordance with the above observations. Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx> --- drivers/acpi/acpi_memhotplug.c | 13 +------ include/linux/memory_hotplug.h | 2 - mm/memory_hotplug.c | 71 ++++------------------------------------- 3 files changed, 12 insertions(+), 74 deletions(-) Index: linux-pm/include/linux/memory_hotplug.h =================================================================== --- linux-pm.orig/include/linux/memory_hotplug.h +++ linux-pm/include/linux/memory_hotplug.h @@ -252,7 +252,7 @@ extern int add_memory(int nid, u64 start extern int arch_add_memory(int nid, u64 start, u64 size); extern int offline_pages(unsigned long start_pfn, unsigned long nr_pages); extern bool is_memblock_offlined(struct memory_block *mem); -extern int remove_memory(int nid, u64 start, u64 size); +extern void remove_memory(int nid, u64 start, u64 size); extern int sparse_add_one_section(struct zone *zone, unsigned long start_pfn, int nr_pages); extern void sparse_remove_one_section(struct zone *zone, struct mem_section *ms); Index: linux-pm/drivers/acpi/acpi_memhotplug.c =================================================================== --- linux-pm.orig/drivers/acpi/acpi_memhotplug.c +++ linux-pm/drivers/acpi/acpi_memhotplug.c @@ -271,13 +271,11 @@ static int acpi_memory_enable_device(str return 0; } -static int acpi_memory_remove_memory(struct acpi_memory_device *mem_device) +static void acpi_memory_remove_memory(struct acpi_memory_device *mem_device) { acpi_handle handle = mem_device->device->handle; - int result = 0, nid; struct acpi_memory_info *info, *n; - - nid = acpi_get_node(handle); + int nid = acpi_get_node(handle); list_for_each_entry_safe(info, n, &mem_device->res_list, list) { if (!info->enabled) @@ -287,15 +285,10 @@ static int acpi_memory_remove_memory(str nid = memory_add_physaddr_to_nid(info->start_addr); acpi_unbind_memory_blocks(info, handle); - result = remove_memory(nid, info->start_addr, info->length); - if (result) - return result; - + remove_memory(nid, info->start_addr, info->length); list_del(&info->list); kfree(info); } - - return result; } static void acpi_memory_device_free(struct acpi_memory_device *mem_device) Index: linux-pm/mm/memory_hotplug.c =================================================================== --- linux-pm.orig/mm/memory_hotplug.c +++ linux-pm/mm/memory_hotplug.c @@ -1670,24 +1670,6 @@ int walk_memory_range(unsigned long star } #ifdef CONFIG_MEMORY_HOTREMOVE -/** - * offline_memory_block_cb - callback function for offlining memory block - * @mem: the memory block to be offlined - * @arg: buffer to hold error msg - * - * Always return 0, and put the error msg in arg if any. - */ -static int offline_memory_block_cb(struct memory_block *mem, void *arg) -{ - int *ret = arg; - int error = device_offline(&mem->dev); - - if (error != 0 && *ret == 0) - *ret = error; - - return 0; -} - static int is_memblock_offlined_cb(struct memory_block *mem, void *arg) { int ret = !is_memblock_offlined(mem); @@ -1813,54 +1795,22 @@ void try_offline_node(int nid) } EXPORT_SYMBOL(try_offline_node); -int __ref remove_memory(int nid, u64 start, u64 size) +void __ref remove_memory(int nid, u64 start, u64 size) { - unsigned long start_pfn, end_pfn; - int ret = 0; - int retry = 1; - - start_pfn = PFN_DOWN(start); - end_pfn = PFN_UP(start + size - 1); - - /* - * When CONFIG_MEMCG is on, one memory block may be used by other - * blocks to store page cgroup when onlining pages. But we don't know - * in what order pages are onlined. So we iterate twice to offline - * memory: - * 1st iterate: offline every non primary memory block. - * 2nd iterate: offline primary (i.e. first added) memory block. - */ -repeat: - walk_memory_range(start_pfn, end_pfn, &ret, - offline_memory_block_cb); - if (ret) { - if (!retry) - return ret; - - retry = 0; - ret = 0; - goto repeat; - } + int ret; lock_memory_hotplug(); /* - * we have offlined all memory blocks like this: - * 1. lock memory hotplug - * 2. offline a memory block - * 3. unlock memory hotplug - * - * repeat step1-3 to offline the memory block. All memory blocks - * must be offlined before removing memory. But we don't hold the - * lock in the whole operation. So we should check whether all - * memory blocks are offlined. + * All memory blocks must be offlined before removing memory. Check + * whether all memory blocks in question are offline and trigger a BUG() + * if this is not the case. */ - - ret = walk_memory_range(start_pfn, end_pfn, NULL, + ret = walk_memory_range(PFN_DOWN(start), PFN_UP(start + size - 1), NULL, is_memblock_offlined_cb); if (ret) { unlock_memory_hotplug(); - return ret; + BUG(); } /* remove memmap entry */ @@ -1871,17 +1821,12 @@ repeat: try_offline_node(nid); unlock_memory_hotplug(); - - return 0; } #else int offline_pages(unsigned long start_pfn, unsigned long nr_pages) { return -EINVAL; } -int remove_memory(int nid, u64 start, u64 size) -{ - return -EINVAL; -} +void remove_memory(int nid, u64 start, u64 size) {} #endif /* CONFIG_MEMORY_HOTREMOVE */ EXPORT_SYMBOL_GPL(remove_memory); -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx"> email@xxxxxxxxx </a>