| Message ID | 20210209133854.17399-4-osalvador@suse.de (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | Allocate memmap from hotadded memory (per device) | expand |
> diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c > index 9bcc460e8bfe..95695483a622 100644 > --- a/mm/memory_hotplug.c > +++ b/mm/memory_hotplug.c > @@ -42,7 +42,31 @@ > #include "internal.h" > #include "shuffle.h" > > -static bool memmap_on_memory_enabled; > +/* > + * memory_hotplug.memmap_on_memory parameter > + */ > +static bool memmap_on_memory_enabled __ro_after_init; > + > +static int memmap_on_memory_show(char *buffer, const struct kernel_param *kp) > +{ > + return sprintf(buffer, "%s\n", > + memmap_on_memory_enabled ? "on" : "off"); > +} > + > +static __meminit int memmap_on_memory_store(const char *val, > + const struct kernel_param *kp) > +{ > + /* > + * Fail silently in case we cannot enable it due to platform constraints. > + * User can always check whether it is enabled or not via /sys/module. > + */ > + if (!IS_ENABLED(CONFIG_ARCH_MHP_MEMMAP_ON_MEMORY_ENABLE)) > + return 0; > + > + return param_set_bool(val, kp); > +} > +module_param_call(memmap_on_memory, memmap_on_memory_store, > + memmap_on_memory_show, &memmap_on_memory_enabled, 0400); Why are other users not allowed to read? > Might want to add a MODULE_PARM_DESC(). As we fail silently already, I'd keep it simple and use a module_param(memmap_on_memory, bool, 0444); moving the IS_ENABLED(CONFIG_ARCH_MHP_MEMMAP_ON_MEMORY_ENABLE) into the runtime check. Apart from that LGTM.
On Thu, Feb 25, 2021 at 07:25:58PM +0100, David Hildenbrand wrote: > > +static __meminit int memmap_on_memory_store(const char *val, > > + const struct kernel_param *kp) > > +{ > > + /* > > + * Fail silently in case we cannot enable it due to platform constraints. > > + * User can always check whether it is enabled or not via /sys/module. > > + */ > > + if (!IS_ENABLED(CONFIG_ARCH_MHP_MEMMAP_ON_MEMORY_ENABLE)) > > + return 0; > > + > > + return param_set_bool(val, kp); > > +} > > +module_param_call(memmap_on_memory, memmap_on_memory_store, > > + memmap_on_memory_show, &memmap_on_memory_enabled, 0400); > > Why are other users not allowed to read? I copied it from the shuffle one. I guess shuffle code made it 0400 for security reasons. Since we do not need that here, I will switch it to 0444. > Might want to add a MODULE_PARM_DESC(). Sure > As we fail silently already, I'd keep it simple and use a > > module_param(memmap_on_memory, bool, 0444); > > moving the IS_ENABLED(CONFIG_ARCH_MHP_MEMMAP_ON_MEMORY_ENABLE) into the > runtime check. You mean moving this check into mhp_supports_memmap_on_memory() check from patch#1 right? Makes sense.
>> module_param(memmap_on_memory, bool, 0444); >> >> moving the IS_ENABLED(CONFIG_ARCH_MHP_MEMMAP_ON_MEMORY_ENABLE) into the >> runtime check. > > You mean moving this check into mhp_supports_memmap_on_memory() check > from patch#1 right? > > Makes sense. Yep.
diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt index 5adf1e57e932..696beb5f6c92 100644 --- a/Documentation/admin-guide/kernel-parameters.txt +++ b/Documentation/admin-guide/kernel-parameters.txt @@ -2811,6 +2811,20 @@ seconds. Use this parameter to check at some other rate. 0 disables periodic checking. + memory_hotplug.memmap_on_memory + [KNL,X86,ARM] Boolean flag to enable this feature. + Format: {on | off (default)} + When enabled, memory to build the pages tables for the + memmap array describing the hot-added range will be taken + from the range itself, so the memmap page tables will be + self-hosted. + Since only single memory device ranges are supported at + the moment, this option is disabled by default because + it might have an impact on workloads that needs large + contiguous memory chunks. + The state of the flag can be read in + /sys/module/memory_hotplug/parameters/memmap_on_memory. + memtest= [KNL,X86,ARM,PPC] Enable memtest Format: <integer> default : 0 <disable> diff --git a/mm/Makefile b/mm/Makefile index b2a564eec27f..9e284dba50ef 100644 --- a/mm/Makefile +++ b/mm/Makefile @@ -58,9 +58,13 @@ obj-y := filemap.o mempool.o oom_kill.o fadvise.o \ page-alloc-y := page_alloc.o page-alloc-$(CONFIG_SHUFFLE_PAGE_ALLOCATOR) += shuffle.o +# Give 'memory_hotplug' its own module-parameter namespace +memory-hotplug-$(CONFIG_MEMORY_HOTPLUG) += memory_hotplug.o + obj-y += page-alloc.o obj-y += init-mm.o obj-y += memblock.o +obj-y += $(memory-hotplug-y) ifdef CONFIG_MMU obj-$(CONFIG_ADVISE_SYSCALLS) += madvise.o @@ -83,7 +87,6 @@ obj-$(CONFIG_SLUB) += slub.o obj-$(CONFIG_KASAN) += kasan/ obj-$(CONFIG_KFENCE) += kfence/ obj-$(CONFIG_FAILSLAB) += failslab.o -obj-$(CONFIG_MEMORY_HOTPLUG) += memory_hotplug.o obj-$(CONFIG_MEMTEST) += memtest.o obj-$(CONFIG_MIGRATION) += migrate.o obj-$(CONFIG_TRANSPARENT_HUGEPAGE) += huge_memory.o khugepaged.o diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c index 9bcc460e8bfe..95695483a622 100644 --- a/mm/memory_hotplug.c +++ b/mm/memory_hotplug.c @@ -42,7 +42,31 @@ #include "internal.h" #include "shuffle.h" -static bool memmap_on_memory_enabled; +/* + * memory_hotplug.memmap_on_memory parameter + */ +static bool memmap_on_memory_enabled __ro_after_init; + +static int memmap_on_memory_show(char *buffer, const struct kernel_param *kp) +{ + return sprintf(buffer, "%s\n", + memmap_on_memory_enabled ? "on" : "off"); +} + +static __meminit int memmap_on_memory_store(const char *val, + const struct kernel_param *kp) +{ + /* + * Fail silently in case we cannot enable it due to platform constraints. + * User can always check whether it is enabled or not via /sys/module. + */ + if (!IS_ENABLED(CONFIG_ARCH_MHP_MEMMAP_ON_MEMORY_ENABLE)) + return 0; + + return param_set_bool(val, kp); +} +module_param_call(memmap_on_memory, memmap_on_memory_store, + memmap_on_memory_show, &memmap_on_memory_enabled, 0400); /* * online_page_callback contains pointer to current page onlining function.
Self stored memmap leads to a sparse memory situation which is unsuitable for workloads that requires large contiguous memory chunks, so make this an opt-in which needs to be explicitly enabled. To control this, let memory_hotplug have its own memory space, as suggested by David, so we can add memory_hotplug.memmap_on_memory parameter. Signed-off-by: Oscar Salvador <osalvador@suse.de> --- Documentation/admin-guide/kernel-parameters.txt | 14 +++++++++++++ mm/Makefile | 5 ++++- mm/memory_hotplug.c | 26 ++++++++++++++++++++++++- 3 files changed, 43 insertions(+), 2 deletions(-)