Commit edeba251 authored by Kefeng Wang's avatar Kefeng Wang
Browse files

mm: filemap: try to enable THP for exec mapping 

hulk inclusion
category: feature
bugzilla: https://gitee.com/openeuler/kernel/issues/I9H84X


CVE: NA

-------------------------------------------------

Let's the do_sync_mmap_readahead() to try to enable THP for exec
mapping, which could ruduce iTLB miss for large application with
big text segment.

Signed-off-by: default avatarKefeng Wang <wangkefeng.wang@huawei.com>
parent adf05a3b

Documentation/admin-guide/mm/transhuge.rst

+7 −0
Original line number Diff line number Diff line
@@ -202,6 +202,13 @@ PMD-mappable transparent hugepage:: 


	cat /sys/kernel/mm/transparent_hugepage/hpage_pmd_size



The kernel tries to use huge, PMD-mappable page on read page fault for

file exec mapping if CONFIG_READ_ONLY_THP_FOR_FS enabled. It's possible

to enabled the feature by writing 1 or disablt by writing 0::



	echo 0x0 >/sys/kernel/mm/transparent_hugepage/thp_exec_enabled

	echo 0x1 >/sys/kernel/mm/transparent_hugepage/thp_exec_enabled



khugepaged will be automatically started when one or more hugepage

sizes are enabled (either by directly setting "always" or "madvise",

or by setting "inherit" while the top-level enabled is set to "always"

include/linux/huge_mm.h

+1 −0
Original line number Diff line number Diff line
@@ -50,6 +50,7 @@ enum transparent_hugepage_flag { 
	TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG,

	TRANSPARENT_HUGEPAGE_DEFRAG_KHUGEPAGED_FLAG,

	TRANSPARENT_HUGEPAGE_USE_ZERO_PAGE_FLAG,

	TRANSPARENT_HUGEPAGE_FILE_EXEC_THP_FLAG,

};



struct kobject;

mm/filemap.c

+27 −0
Original line number Diff line number Diff line
@@ -45,6 +45,7 @@ 
#include <linux/migrate.h>

#include <linux/pipe_fs_i.h>

#include <linux/splice.h>

#include <linux/huge_mm.h>

#include <asm/pgalloc.h>

#include <asm/tlbflush.h>

#include "internal.h"
@@ -3113,6 +3114,29 @@ static int lock_folio_maybe_drop_mmap(struct vm_fault *vmf, struct folio *folio, 
	return 1;

}



#ifdef CONFIG_TRANSPARENT_HUGEPAGE

#define file_exec_thp_enabled()				\

	(transparent_hugepage_flags &			\

	 (1<<TRANSPARENT_HUGEPAGE_FILE_EXEC_THP_FLAG))



static inline void try_enable_file_exec_thp(struct vm_area_struct *vma,

					    unsigned long *vm_flags,

					    struct file *file)

{

	if (!IS_ENABLED(CONFIG_READ_ONLY_THP_FOR_FS))

		return;



	if (!is_exec_mapping(*vm_flags))

		return;



	if (file->f_op->get_unmapped_area != thp_get_unmapped_area)

		return;



	if (file_exec_thp_enabled())

		hugepage_madvise(vma, vm_flags, MADV_HUGEPAGE);

}

#endif



/*

 * Synchronous readahead happens when we don't even find a page in the page

 * cache at all.  We don't want to perform IO under the mmap sem, so if we have
@@ -3131,6 +3155,9 @@ static struct file *do_sync_mmap_readahead(struct vm_fault *vmf) 
	unsigned int mmap_miss;



#ifdef CONFIG_TRANSPARENT_HUGEPAGE

	/* Try enable thp for exec mapping by default */

	try_enable_file_exec_thp(vmf->vma, &vm_flags, file);



	/* Use the readahead code, even if readahead is disabled */

	if (vm_flags & VM_HUGEPAGE) {

		fpin = maybe_unlock_mmap_for_io(vmf, fpin);

mm/huge_memory.c

+29 −0
Original line number Diff line number Diff line
@@ -425,6 +425,32 @@ static ssize_t hpage_pmd_size_show(struct kobject *kobj, 
static struct kobj_attribute hpage_pmd_size_attr =

	__ATTR_RO(hpage_pmd_size);



#ifdef CONFIG_READ_ONLY_THP_FOR_FS

static ssize_t thp_exec_enabled_show(struct kobject *kobj,

				     struct kobj_attribute *attr, char *buf)

{

	return single_hugepage_flag_show(kobj, attr, buf,

				 TRANSPARENT_HUGEPAGE_FILE_EXEC_THP_FLAG);

}

static ssize_t thp_exec_enabled_store(struct kobject *kobj,

		struct kobj_attribute *attr, const char *buf, size_t count)

{

	size_t ret = single_hugepage_flag_store(kobj, attr, buf, count,

				 TRANSPARENT_HUGEPAGE_FILE_EXEC_THP_FLAG);

	if (ret > 0) {

		int err = start_stop_khugepaged();



		if (err)

			ret = err;

	}



	return ret;

}

static struct kobj_attribute thp_exec_enabled_attr =

	__ATTR_RW(thp_exec_enabled);



#endif



static struct attribute *hugepage_attr[] = {

	&enabled_attr.attr,

	&defrag_attr.attr,
@@ -432,6 +458,9 @@ static struct attribute *hugepage_attr[] = { 
	&hpage_pmd_size_attr.attr,

#ifdef CONFIG_SHMEM

	&shmem_enabled_attr.attr,

#endif

#ifdef CONFIG_READ_ONLY_THP_FOR_FS

	&thp_exec_enabled_attr.attr,

#endif

	NULL,

};