Hello Jungseok, On Mon, May 25, 2015 at 01:02:20AM +0900, Jungseok Lee wrote: > Fork-routine sometimes fails to get a physically contiguous region for > thread_info on 4KB page system although free memory is enough. That is, > a physically contiguous region, which is currently 16KB, is not available > since system memory is fragmented. Order less than PAGE_ALLOC_COSTLY_ORDER should not fail in current mm implementation. If you saw the order-2,3 high-order allocation fail maybe your application received SIGKILL by someone. LMK? > > This patch tries to solve the problem as allocating thread_info memory > from vmalloc space, not 1:1 mapping one. The downside is one additional > page allocation in case of vmalloc. However, vmalloc space is large enough, The size you want to allocate is 16KB in here but additional 4K? It increases 25% memory footprint, which is huge downside. > around 240GB, under a combination of 39-bit VA and 4KB page. Thus, it is > not a big tradeoff for fork-routine service. > > Suggested-by: Sungjinn Chung <barami97@xxxxxxxxx> > Signed-off-by: Jungseok Lee <jungseoklee85@xxxxxxxxx> > Cc: Catalin Marinas <catalin.marinas@xxxxxxx> > Cc: Will Deacon <will.deacon@xxxxxxx> > Cc: linux-kernel@xxxxxxxxxxxxxxx > Cc: linux-mm@xxxxxxxxx > --- > arch/arm64/Kconfig | 12 ++++++++++++ > arch/arm64/include/asm/thread_info.h | 9 +++++++++ > arch/arm64/kernel/process.c | 7 +++++++ > 3 files changed, 28 insertions(+) > > diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig > index 99930cf..93c236a 100644 > --- a/arch/arm64/Kconfig > +++ b/arch/arm64/Kconfig > @@ -536,6 +536,18 @@ config ARCH_SELECT_MEMORY_MODEL > config HAVE_ARCH_PFN_VALID > def_bool ARCH_HAS_HOLES_MEMORYMODEL || !SPARSEMEM > > +config ARCH_THREAD_INFO_ALLOCATOR > + bool "Enable vmalloc based thread_info allocator (EXPERIMENTAL)" > + depends on ARM64_4K_PAGES > + default n > + help > + This feature enables vmalloc based thread_info allocator. It > + prevents fork-routine from begin failed to obtain physically > + contiguour region due to memory fragmentation on low system > + memory platforms. > + > + If unsure, say N > + > config HW_PERF_EVENTS > bool "Enable hardware performance counter support for perf events" > depends on PERF_EVENTS > diff --git a/arch/arm64/include/asm/thread_info.h b/arch/arm64/include/asm/thread_info.h > index dcd06d1..e753e59 100644 > --- a/arch/arm64/include/asm/thread_info.h > +++ b/arch/arm64/include/asm/thread_info.h > @@ -61,6 +61,15 @@ struct thread_info { > #define init_thread_info (init_thread_union.thread_info) > #define init_stack (init_thread_union.stack) > > +#ifdef CONFIG_ARCH_THREAD_INFO_ALLOCATOR > +#define alloc_thread_info_node(tsk, node) \ > +({ \ > + __vmalloc_node_range(THREAD_SIZE, THREAD_SIZE, VMALLOC_START, \ > + VMALLOC_END, GFP_KERNEL, PAGE_KERNEL, 0, \ > + NUMA_NO_NODE, __builtin_return_address(0)); \ > +}) > +#define free_thread_info(ti) vfree(ti) > +#endif > /* > * how to get the current stack pointer from C > */ > diff --git a/arch/arm64/kernel/process.c b/arch/arm64/kernel/process.c > index c506bee..c4b6aae 100644 > --- a/arch/arm64/kernel/process.c > +++ b/arch/arm64/kernel/process.c > @@ -238,6 +238,13 @@ int arch_dup_task_struct(struct task_struct *dst, struct task_struct *src) > return 0; > } > > +#ifdef CONFIG_ARCH_THREAD_INFO_ALLOCATOR > +struct page *arch_thread_info_to_page(struct thread_info *ti) > +{ > + return vmalloc_to_page(ti); > +} > +#endif > + > asmlinkage void ret_from_fork(void) asm("ret_from_fork"); > > int copy_thread(unsigned long clone_flags, unsigned long stack_start, > -- > 1.9.1 > > -- > 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> -- Kind regards, Minchan Kim -- 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>