Setting /proc/sys/fs/file-max larger than 2^63 on a 64-bit system is
wrong since the kernel cannot allocate that many structures (similarly
2^31 for a 32-bit system).
This will also cause an integer overflow in the check in unix_create1():
atomic_long_read(&unix_nr_socks) > 2 * get_max_files()
which prevents the kernel from creating a unix domain socket when the
sysadmin sets a large file-max.
Suggested-by: Eric Dumazet <[email protected]>
Signed-off-by: Xi Wang <[email protected]>
---
What's the best min value for file-max? This patch uses NR_FILE.
Zero seems weird. BITS_PER_LONG as sysctl_nr_open_min?
---
fs/file_table.c | 8 ++++++--
kernel/sysctl.c | 3 +++
2 files changed, 9 insertions(+), 2 deletions(-)
diff --git a/fs/file_table.c b/fs/file_table.c
index 701985e..9b65e59 100644
--- a/fs/file_table.c
+++ b/fs/file_table.c
@@ -36,6 +36,9 @@ struct files_stat_struct files_stat = {
.max_files = NR_FILE
};
+unsigned long sysctl_file_max_min = NR_FILE;
+unsigned long sysctl_file_max_max = NR_FILE; /* raised later */
+
DEFINE_LGLOCK(files_lglock);
/* SLAB cache for file structures */
@@ -582,8 +585,9 @@ void __init files_init(unsigned long mempages)
* Per default don't use more than 10% of our memory for files.
*/
- n = (mempages * (PAGE_SIZE / 1024)) / 10;
- files_stat.max_files = max_t(unsigned long, n, NR_FILE);
+ n = mempages * (PAGE_SIZE / 1024);
+ files_stat.max_files = max_t(unsigned long, n / 10, NR_FILE);
+ sysctl_file_max_max = max_t(unsigned long, n, NR_FILE);
files_defer_init();
lg_lock_init(&files_lglock, "files_lglock");
percpu_counter_init(&nr_files, 0);
diff --git a/kernel/sysctl.c b/kernel/sysctl.c
index 87174ef..a21e22a 100644
--- a/kernel/sysctl.c
+++ b/kernel/sysctl.c
@@ -108,6 +108,7 @@ extern int sysctl_drop_caches;
extern int percpu_pagelist_fraction;
extern int compat_log;
extern int latencytop_enabled;
+extern int sysctl_file_max_min, sysctl_file_max_max;
extern int sysctl_nr_open_min, sysctl_nr_open_max;
#ifndef CONFIG_MMU
extern int sysctl_nr_trim_pages;
@@ -1403,6 +1404,8 @@ static struct ctl_table fs_table[] = {
.maxlen = sizeof(files_stat.max_files),
.mode = 0644,
.proc_handler = proc_doulongvec_minmax,
+ .extra1 = &sysctl_file_max_min,
+ .extra2 = &sysctl_file_max_max,
},
{
.procname = "nr_open",
--
1.7.9.5
--
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