diff mbox series

[v2] mm/ksm: introduce ksm_force for each process

Message ID 20220507014318.642353-1-xu.xin16@zte.com.cn (mailing list archive)
State New
Headers show
Series [v2] mm/ksm: introduce ksm_force for each process | expand

Commit Message

CGEL May 7, 2022, 1:43 a.m. UTC 
From: xu xin <xu.xin16@zte.com.cn>

To use KSM, we must explicitly call madvise() in application code,
which means installed apps on OS needs to be uninstall and source
code needs to be modified. It is inconvenient.

In order to change this situation, We add a new proc 'ksm_force'
under /proc/<pid>/ to support turning on/off KSM scanning of a
process's mm dynamically.

If ksm_force is set as 1, force all anonymous and 'qualified' vma
of this mm to be involved in KSM scanning without explicitly
calling madvise to make vma MADV_MERGEABLE. But It is effctive only
when the klob of '/sys/kernel/mm/ksm/run' is set as 1.

If ksm_enale is set as 0, cancel the feature of ksm_force of this
process and unmerge those merged pages which is not madvised as
MERGEABLE of this process, but leave MERGEABLE areas merged.

Signed-off-by: xu xin <xu.xin16@zte.com.cn>
Reviewed-by: Yang Yang <yang.yang29@zte.com.cn>
Reviewed-by: Ran Xiaokai <ran.xiaokai@zte.com.cn>
Reviewed-by: wangyong <wang.yong12@zte.com.cn>
Reviewed-by: Yunkai Zhang <zhang.yunkai@zte.com.cn>
---
v2:
- fix a spelling error in commit log.
- remove a redundant condition check in ksm_force_write().

---
 fs/proc/base.c           | 99 ++++++++++++++++++++++++++++++++++++++++
 include/linux/mm_types.h |  9 ++++
 mm/ksm.c                 | 32 ++++++++++++-
 3 files changed, 138 insertions(+), 2 deletions(-)

Comments

kernel test robot May 7, 2022, 4:33 a.m. UTC | #1 
Hi,

Thank you for the patch! Yet something to improve:

[auto build test ERROR on akpm-mm/mm-everything]
[also build test ERROR on next-20220506]
[cannot apply to hnaz-mm/master kees/for-next/pstore linus/master v5.18-rc5]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch]

url:    https://github.com/intel-lab-lkp/linux/commits/cgel-zte-gmail-com/mm-ksm-introduce-ksm_force-for-each-process/20220507-094557
base:   https://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm.git mm-everything
config: arc-allyesconfig (https://download.01.org/0day-ci/archive/20220507/202205071213.kLZzW7OV-lkp@intel.com/config)
compiler: arceb-elf-gcc (GCC) 11.3.0
reproduce (this is a W=1 build):
        wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
        chmod +x ~/bin/make.cross
        # https://github.com/intel-lab-lkp/linux/commit/bc6a122b9e10290755c811e7fa23dd60d39303e2
        git remote add linux-review https://github.com/intel-lab-lkp/linux
        git fetch --no-tags linux-review cgel-zte-gmail-com/mm-ksm-introduce-ksm_force-for-each-process/20220507-094557
        git checkout bc6a122b9e10290755c811e7fa23dd60d39303e2
        # save the config file
        mkdir build_dir && cp config build_dir/.config
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-11.3.0 make.cross W=1 O=build_dir ARCH=arc SHELL=/bin/bash

If you fix the issue, kindly add following tag as appropriate
Reported-by: kernel test robot <lkp@intel.com>

All errors (new ones prefixed by >>):

   mm/ksm.c: In function 'ksm_vma_check':
>> mm/ksm.c:343:17: error: 'turn' undeclared (first use in this function)
     343 |                 turn false;
         |                 ^~~~
   mm/ksm.c:343:17: note: each undeclared identifier is reported only once for each function it appears in
>> mm/ksm.c:343:21: error: expected ';' before 'false'
     343 |                 turn false;
         |                     ^~~~~~
         |                     ;


vim +/turn +343 mm/ksm.c

   336	
   337	/* Check if vma is qualified for ksmd scanning */
   338	static bool ksm_vma_check(struct vm_area_struct *vma)
   339	{
   340		unsigned long vm_flags = vma->vm_flags;
   341	
   342		if (!(vma->vm_flags & VM_MERGEABLE) && !(vma->vm_mm->ksm_force))
 > 343			turn false;
   344	
   345		if (vm_flags & (VM_SHARED	| VM_MAYSHARE	|
   346				VM_PFNMAP	| VM_IO | VM_DONTEXPAND |
   347				VM_HUGETLB	| VM_MIXEDMAP))
   348			return false;       /* just ignore this vma*/
   349	
   350		if (vma_is_dax(vma))
   351			return false;
   352
kernel test robot May 7, 2022, 4:49 a.m. UTC | #2 
Hi,

Thank you for the patch! Yet something to improve:

[auto build test ERROR on akpm-mm/mm-everything]
[also build test ERROR on next-20220506]
[cannot apply to hnaz-mm/master kees/for-next/pstore linus/master v5.18-rc5]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch]

url:    https://github.com/intel-lab-lkp/linux/commits/cgel-zte-gmail-com/mm-ksm-introduce-ksm_force-for-each-process/20220507-094557
base:   https://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm.git mm-everything
config: hexagon-randconfig-r045-20220506 (https://download.01.org/0day-ci/archive/20220507/202205071229.7ltA0xmX-lkp@intel.com/config)
compiler: clang version 15.0.0 (https://github.com/llvm/llvm-project af4cf1c6b8ed0d8102fc5e69acdc2fcbbcdaa9a7)
reproduce (this is a W=1 build):
        wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
        chmod +x ~/bin/make.cross
        # https://github.com/intel-lab-lkp/linux/commit/bc6a122b9e10290755c811e7fa23dd60d39303e2
        git remote add linux-review https://github.com/intel-lab-lkp/linux
        git fetch --no-tags linux-review cgel-zte-gmail-com/mm-ksm-introduce-ksm_force-for-each-process/20220507-094557
        git checkout bc6a122b9e10290755c811e7fa23dd60d39303e2
        # save the config file
        mkdir build_dir && cp config build_dir/.config
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross W=1 O=build_dir ARCH=hexagon SHELL=/bin/bash

If you fix the issue, kindly add following tag as appropriate
Reported-by: kernel test robot <lkp@intel.com>

All errors (new ones prefixed by >>):

>> mm/ksm.c:343:3: error: use of undeclared identifier 'turn'
                   turn false;
                   ^
   1 error generated.


vim +/turn +343 mm/ksm.c

   336	
   337	/* Check if vma is qualified for ksmd scanning */
   338	static bool ksm_vma_check(struct vm_area_struct *vma)
   339	{
   340		unsigned long vm_flags = vma->vm_flags;
   341	
   342		if (!(vma->vm_flags & VM_MERGEABLE) && !(vma->vm_mm->ksm_force))
 > 343			turn false;
   344	
   345		if (vm_flags & (VM_SHARED	| VM_MAYSHARE	|
   346				VM_PFNMAP	| VM_IO | VM_DONTEXPAND |
   347				VM_HUGETLB	| VM_MIXEDMAP))
   348			return false;       /* just ignore this vma*/
   349	
   350		if (vma_is_dax(vma))
   351			return false;
   352
diff mbox series

Patch

diff --git a/fs/proc/base.c b/fs/proc/base.c
index 8dfa36a99c74..3115ffa4c9fb 100644
--- a/fs/proc/base.c
+++ b/fs/proc/base.c
@@ -96,6 +96,7 @@ 
 #include <linux/time_namespace.h>
 #include <linux/resctrl.h>
 #include <linux/cn_proc.h>
+#include <linux/ksm.h>
 #include <trace/events/oom.h>
 #include "internal.h"
 #include "fd.h"
@@ -3168,6 +3169,102 @@  static int proc_pid_ksm_merging_pages(struct seq_file *m, struct pid_namespace *
 
 	return 0;
 }
+
+static ssize_t ksm_force_read(struct file *file, char __user *buf, size_t count,
+				loff_t *ppos)
+{
+	struct task_struct *task;
+	struct mm_struct *mm;
+	char buffer[PROC_NUMBUF];
+	ssize_t len;
+	int ret;
+
+	task = get_proc_task(file_inode(file));
+	if (!task)
+		return -ESRCH;
+
+	mm = get_task_mm(task);
+	ret = 0;
+	if (mm) {
+		len = snprintf(buffer, sizeof(buffer), "%d\n", mm->ksm_force);
+		ret =  simple_read_from_buffer(buf, count, ppos, buffer, len);
+		mmput(mm);
+	}
+
+	return ret;
+}
+
+static ssize_t ksm_force_write(struct file *file, const char __user *buf,
+				size_t count, loff_t *ppos)
+{
+	struct task_struct *task;
+	struct mm_struct *mm;
+	char buffer[PROC_NUMBUF];
+	int force;
+	int err = 0;
+
+	memset(buffer, 0, sizeof(buffer));
+	if (count > sizeof(buffer) - 1)
+		count = sizeof(buffer) - 1;
+	if (copy_from_user(buffer, buf, count)) {
+		err = -EFAULT;
+		goto out_return;
+	}
+
+	err = kstrtoint(strstrip(buffer), 0, &force);
+
+	if (err)
+		goto out_return;
+	if (force != 0 && force != 1) {
+		err = -EINVAL;
+		goto out_return;
+	}
+
+	task = get_proc_task(file_inode(file));
+	if (!task) {
+		err = -ESRCH;
+		goto out_return;
+	}
+
+	mm = get_task_mm(task);
+	if (!mm)
+		goto out_put_task;
+
+	if (mm->ksm_force != force) {
+		if (mmap_write_lock_killable(mm)) {
+			err = -EINTR;
+			goto out_mmput;
+		}
+
+		if (force == 0)
+			mm->ksm_force = force;
+		else {
+			/*
+			 * Force anonymous pages of this mm to be involved in KSM merging
+			 * without explicitly calling madvise.
+			 */
+			if (!test_bit(MMF_VM_MERGEABLE, &mm->flags))
+				err = __ksm_enter(mm);
+			if (!err)
+				mm->ksm_force = force;
+		}
+
+		mmap_write_unlock(mm);
+	}
+
+out_mmput:
+	mmput(mm);
+out_put_task:
+	put_task_struct(task);
+out_return:
+	return err < 0 ? err : count;
+}
+
+static const struct file_operations proc_pid_ksm_force_operations = {
+	.read		= ksm_force_read,
+	.write		= ksm_force_write,
+	.llseek		= generic_file_llseek,
+};
 #endif /* CONFIG_KSM */
 
 #ifdef CONFIG_STACKLEAK_METRICS
@@ -3303,6 +3400,7 @@  static const struct pid_entry tgid_base_stuff[] = {
 #endif
 #ifdef CONFIG_KSM
 	ONE("ksm_merging_pages",  S_IRUSR, proc_pid_ksm_merging_pages),
+	REG("ksm_force", S_IRUSR|S_IWUSR, proc_pid_ksm_force_operations),
 #endif
 };
 
@@ -3639,6 +3737,7 @@  static const struct pid_entry tid_base_stuff[] = {
 #endif
 #ifdef CONFIG_KSM
 	ONE("ksm_merging_pages",  S_IRUSR, proc_pid_ksm_merging_pages),
+	REG("ksm_force", S_IRUSR|S_IWUSR, proc_pid_ksm_force_operations),
 #endif
 };
 
diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h
index b34ff2cdbc4f..1b1592c2f5cf 100644
--- a/include/linux/mm_types.h
+++ b/include/linux/mm_types.h
@@ -661,6 +661,15 @@  struct mm_struct {
 		 * merging.
 		 */
 		unsigned long ksm_merging_pages;
+		/*
+		 * If true, force anonymous pages of this mm to be involved in KSM
+		 * merging without explicitly calling madvise. It is effctive only
+		 * when the klob of '/sys/kernel/mm/ksm/run' is set as 1. If false,
+		 * cancel the feature of ksm_force of this process and unmerge
+		 * those merged pages which is not madvised as MERGEABLE of this
+		 * process, but leave MERGEABLE areas merged.
+		 */
+		bool ksm_force;
 #endif
 	} __randomize_layout;
 
diff --git a/mm/ksm.c b/mm/ksm.c
index 38360285497a..ba170e53e283 100644
--- a/mm/ksm.c
+++ b/mm/ksm.c
@@ -334,6 +334,34 @@  static void __init ksm_slab_free(void)
 	mm_slot_cache = NULL;
 }
 
+/* Check if vma is qualified for ksmd scanning */
+static bool ksm_vma_check(struct vm_area_struct *vma)
+{
+	unsigned long vm_flags = vma->vm_flags;
+
+	if (!(vma->vm_flags & VM_MERGEABLE) && !(vma->vm_mm->ksm_force))
+		turn false;
+
+	if (vm_flags & (VM_SHARED	| VM_MAYSHARE	|
+			VM_PFNMAP	| VM_IO | VM_DONTEXPAND |
+			VM_HUGETLB	| VM_MIXEDMAP))
+		return false;       /* just ignore this vma*/
+
+	if (vma_is_dax(vma))
+		return false;
+
+#ifdef VM_SAO
+	if (vm_flags & VM_SAO)
+		return false;
+#endif
+#ifdef VM_SPARC_ADI
+	if (vm_flags & VM_SPARC_ADI)
+		return false;
+#endif
+
+	return true;
+}
+
 static __always_inline bool is_stable_node_chain(struct stable_node *chain)
 {
 	return chain->rmap_hlist_len == STABLE_NODE_CHAIN;
@@ -523,7 +551,7 @@  static struct vm_area_struct *find_mergeable_vma(struct mm_struct *mm,
 	if (ksm_test_exit(mm))
 		return NULL;
 	vma = vma_lookup(mm, addr);
-	if (!vma || !(vma->vm_flags & VM_MERGEABLE) || !vma->anon_vma)
+	if (!vma || !ksm_vma_check(vma) || !vma->anon_vma)
 		return NULL;
 	return vma;
 }
@@ -2297,7 +2325,7 @@  static struct rmap_item *scan_get_next_rmap_item(struct page **page)
 		vma = find_vma(mm, ksm_scan.address);
 
 	for (; vma; vma = vma->vm_next) {
-		if (!(vma->vm_flags & VM_MERGEABLE))
+		if (!ksm_vma_check(vma))
 			continue;
 		if (ksm_scan.address < vma->vm_start)
 			ksm_scan.address = vma->vm_start;