This moves all mmap related sysctls to its own file, as part of the
kernel/sysctl.c cleaning, also move the variable declaration from
kernel/sysctl.c into mm/mmap.c. Besides, move MAPCOUNT_ELF_CORE_MARGIN
and DEFAULT_MAX_MAP_COUNT into mmap.c from mm.h.
Signed-off-by: Kaixiong Yu <yukaixiong@xxxxxxxxxx>
---
include/linux/mm.h | 19 ------------
kernel/sysctl.c | 50 +------------------------------
mm/mmap.c | 75 ++++++++++++++++++++++++++++++++++++++++++++++
mm/util.c | 1 -
4 files changed, 76 insertions(+), 69 deletions(-)
diff --git a/include/linux/mm.h b/include/linux/mm.h
index a04543984a46..9400c92b4522 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -176,25 +176,6 @@ static inline void __mm_zero_struct_page(struct page *page)
#define mm_zero_struct_page(pp) ((void)memset((pp), 0, sizeof(struct page)))
#endif
-/*
- * Default maximum number of active map areas, this limits the number of vmas
- * per mm struct. Users can overwrite this number by sysctl but there is a
- * problem.
- *
- * When a program's coredump is generated as ELF format, a section is created
- * per a vma. In ELF, the number of sections is represented in unsigned short.
- * This means the number of sections should be smaller than 65535 at coredump.
- * Because the kernel adds some informative sections to a image of program at
- * generating coredump, we need some margin. The number of extra sections is
- * 1-3 now and depends on arch. We use "5" as safe margin, here.
- *
- * ELF extended numbering allows more than 65535 sections, so 16-bit bound is
- * not a hard limit any more. Although some userspace tools can be surprised by
- * that.
- */
-#define MAPCOUNT_ELF_CORE_MARGIN (5)
-#define DEFAULT_MAX_MAP_COUNT (USHRT_MAX - MAPCOUNT_ELF_CORE_MARGIN)
-
extern int sysctl_max_map_count;
extern unsigned long sysctl_user_reserve_kbytes;
diff --git a/kernel/sysctl.c b/kernel/sysctl.c
index ad3ac6f6c808..41d4afc978e6 100644
--- a/kernel/sysctl.c
+++ b/kernel/sysctl.c
@@ -127,12 +127,6 @@ enum sysctl_writes_mode {
static enum sysctl_writes_mode sysctl_writes_strict = SYSCTL_WRITES_STRICT;
#endif /* CONFIG_PROC_SYSCTL */
-
-#if defined(HAVE_ARCH_PICK_MMAP_LAYOUT) || \
- defined(CONFIG_ARCH_WANT_DEFAULT_TOPDOWN_MMAP_LAYOUT)
-int sysctl_legacy_va_layout;
-#endif
-
#endif /* CONFIG_SYSCTL */
/*
@@ -2047,16 +2041,7 @@ static struct ctl_table vm_table[] = {
.extra1 = SYSCTL_ONE,
.extra2 = SYSCTL_FOUR,
},
-#ifdef CONFIG_MMU
- {
- .procname = "max_map_count",
- .data = &sysctl_max_map_count,
- .maxlen = sizeof(sysctl_max_map_count),
- .mode = 0644,
- .proc_handler = proc_dointvec_minmax,
- .extra1 = SYSCTL_ZERO,
- },
-#else
+#ifndef CONFIG_MMU
{
.procname = "nr_trim_pages",
.data = &sysctl_nr_trim_pages,
@@ -2074,17 +2059,6 @@ static struct ctl_table vm_table[] = {
.proc_handler = proc_dointvec_minmax,
.extra1 = SYSCTL_ZERO,
},
-#if defined(HAVE_ARCH_PICK_MMAP_LAYOUT) || \
- defined(CONFIG_ARCH_WANT_DEFAULT_TOPDOWN_MMAP_LAYOUT)
- {
- .procname = "legacy_va_layout",
- .data = &sysctl_legacy_va_layout,
- .maxlen = sizeof(sysctl_legacy_va_layout),
- .mode = 0644,
- .proc_handler = proc_dointvec_minmax,
- .extra1 = SYSCTL_ZERO,
- },
-#endif
#ifdef CONFIG_MMU
{
.procname = "mmap_min_addr",
@@ -2110,28 +2084,6 @@ static struct ctl_table vm_table[] = {
.extra1 = SYSCTL_ZERO,
},
#endif
-#ifdef CONFIG_HAVE_ARCH_MMAP_RND_BITS
- {
- .procname = "mmap_rnd_bits",
- .data = &mmap_rnd_bits,
- .maxlen = sizeof(mmap_rnd_bits),
- .mode = 0600,
- .proc_handler = proc_dointvec_minmax,
- .extra1 = (void *)&mmap_rnd_bits_min,
- .extra2 = (void *)&mmap_rnd_bits_max,
- },
-#endif
-#ifdef CONFIG_HAVE_ARCH_MMAP_RND_COMPAT_BITS
- {
- .procname = "mmap_rnd_compat_bits",
- .data = &mmap_rnd_compat_bits,
- .maxlen = sizeof(mmap_rnd_compat_bits),
- .mode = 0600,
- .proc_handler = proc_dointvec_minmax,
- .extra1 = (void *)&mmap_rnd_compat_bits_min,
- .extra2 = (void *)&mmap_rnd_compat_bits_max,
- },
-#endif
};
int __init sysctl_init_bases(void)
diff --git a/mm/mmap.c b/mm/mmap.c
index 88524a3768f6..2b37d8fb997f 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -62,6 +62,27 @@
#define arch_mmap_check(addr, len, flags) (0)
#endif
+/*
+ * Default maximum number of active map areas, this limits the number of vmas
+ * per mm struct. Users can overwrite this number by sysctl but there is a
+ * problem.
+ *
+ * When a program's coredump is generated as ELF format, a section is created
+ * per a vma. In ELF, the number of sections is represented in unsigned short.
+ * This means the number of sections should be smaller than 65535 at coredump.
+ * Because the kernel adds some informative sections to a image of program at
+ * generating coredump, we need some margin. The number of extra sections is
+ * 1-3 now and depends on arch. We use "5" as safe margin, here.
+ *
+ * ELF extended numbering allows more than 65535 sections, so 16-bit bound is
+ * not a hard limit any more. Although some userspace tools can be surprised by
+ * that.
+ */
+#define MAPCOUNT_ELF_CORE_MARGIN (5)
+#define DEFAULT_MAX_MAP_COUNT (USHRT_MAX - MAPCOUNT_ELF_CORE_MARGIN)
+
+int sysctl_max_map_count __read_mostly = DEFAULT_MAX_MAP_COUNT;
+
#ifdef CONFIG_HAVE_ARCH_MMAP_RND_BITS
const int mmap_rnd_bits_min = CONFIG_ARCH_MMAP_RND_BITS_MIN;
int mmap_rnd_bits_max __ro_after_init = CONFIG_ARCH_MMAP_RND_BITS_MAX;
@@ -2171,6 +2192,57 @@ struct vm_area_struct *_install_special_mapping(
&special_mapping_vmops);
}
+#ifdef CONFIG_SYSCTL
+#if defined(HAVE_ARCH_PICK_MMAP_LAYOUT) || \
+ defined(CONFIG_ARCH_WANT_DEFAULT_TOPDOWN_MMAP_LAYOUT)
+int sysctl_legacy_va_layout;
+#endif
+
+static struct ctl_table mmap_table[] = {
+ {
+ .procname = "max_map_count",
+ .data = &sysctl_max_map_count,
+ .maxlen = sizeof(sysctl_max_map_count),
+ .mode = 0644,
+ .proc_handler = proc_dointvec_minmax,
+ .extra1 = SYSCTL_ZERO,
+ },
+#if defined(HAVE_ARCH_PICK_MMAP_LAYOUT) || \
+ defined(CONFIG_ARCH_WANT_DEFAULT_TOPDOWN_MMAP_LAYOUT)
+ {
+ .procname = "legacy_va_layout",
+ .data = &sysctl_legacy_va_layout,
+ .maxlen = sizeof(sysctl_legacy_va_layout),
+ .mode = 0644,
+ .proc_handler = proc_dointvec_minmax,
+ .extra1 = SYSCTL_ZERO,
+ },
+#endif
+#ifdef CONFIG_HAVE_ARCH_MMAP_RND_BITS
+ {
+ .procname = "mmap_rnd_bits",
+ .data = &mmap_rnd_bits,
+ .maxlen = sizeof(mmap_rnd_bits),
+ .mode = 0600,
+ .proc_handler = proc_dointvec_minmax,
+ .extra1 = (void *)&mmap_rnd_bits_min,
+ .extra2 = (void *)&mmap_rnd_bits_max,
+ },
+#endif
+#ifdef CONFIG_HAVE_ARCH_MMAP_RND_COMPAT_BITS
+ {
+ .procname = "mmap_rnd_compat_bits",
+ .data = &mmap_rnd_compat_bits,
+ .maxlen = sizeof(mmap_rnd_compat_bits),
+ .mode = 0600,
+ .proc_handler = proc_dointvec_minmax,
+ .extra1 = (void *)&mmap_rnd_compat_bits_min,
+ .extra2 = (void *)&mmap_rnd_compat_bits_max,
+ },
+#endif
+};
+#endif /* CONFIG_SYSCTL */
+
/*
* initialise the percpu counter for VM
*/
@@ -2180,6 +2252,9 @@ void __init mmap_init(void)
ret = percpu_counter_init(&vm_committed_as, 0, GFP_KERNEL);
VM_BUG_ON(ret);
+#ifdef CONFIG_SYSCTL
+ register_sysctl_init("vm", mmap_table);
+#endif
}
/*
diff --git a/mm/util.c b/mm/util.c
index 04a677f04ca9..7f687563b8c7 100644
--- a/mm/util.c
+++ b/mm/util.c
@@ -906,7 +906,6 @@ EXPORT_SYMBOL(folio_mc_copy);
int sysctl_overcommit_memory __read_mostly = OVERCOMMIT_GUESS;
static int sysctl_overcommit_ratio __read_mostly = 50;
static unsigned long sysctl_overcommit_kbytes __read_mostly;
-int sysctl_max_map_count __read_mostly = DEFAULT_MAX_MAP_COUNT;
unsigned long sysctl_user_reserve_kbytes __read_mostly = 1UL << 17; /* 128MB */
unsigned long sysctl_admin_reserve_kbytes __read_mostly = 1UL << 13; /* 8MB */
--
2.25.1
