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swap: add a limit for readahead page-cluster value

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Currenty there is no upper limit for /proc/sys/vm/page-cluster, and it's a
bit shift value, so it could result in overflow of the 32-bit integer. 
Add a reasonable upper limit for it, read-in at most 2**31 pages, which is
a large enough value for readahead.

Link: https://lkml.kernel.org/r/20221023162533.81561-1-ryncsn@gmail.com
Signed-off-by: Kairui Song <kasong@tencent.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
Kairui Song
2022-10-24 00:25:33 +08:00
committed by Andrew Morton
parent 5033091de8
commit ea0ffd0c08
3 changed files with 4 additions and 1 deletions
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1
include/linux/mm.h
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@@ -74,6 +74,7 @@ static inline void totalram_pages_add(long count)
extern void * high_memory; extern void * high_memory;
extern int page_cluster; extern int page_cluster;
extern const int page_cluster_max;
#ifdef CONFIG_SYSCTL #ifdef CONFIG_SYSCTL
extern int sysctl_legacy_va_layout; extern int sysctl_legacy_va_layout;

1
kernel/sysctl.c
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@@ -2125,6 +2125,7 @@ static struct ctl_table vm_table[] = {
.mode = 0644, .mode = 0644,
.proc_handler = proc_dointvec_minmax, .proc_handler = proc_dointvec_minmax,
.extra1 = SYSCTL_ZERO, .extra1 = SYSCTL_ZERO,
.extra2 = (void *)&page_cluster_max,
}, },
{ {
.procname = "dirtytime_expire_seconds", .procname = "dirtytime_expire_seconds",

3
mm/swap.c
View File

@@ -43,8 +43,9 @@
#define CREATE_TRACE_POINTS #define CREATE_TRACE_POINTS
#include <trace/events/pagemap.h> #include <trace/events/pagemap.h>
/* How many pages do we try to swap or page in/out together? */ /* How many pages do we try to swap or page in/out together? As a power of 2 */
int page_cluster; int page_cluster;
const int page_cluster_max = 31;
/* Protecting only lru_rotate.fbatch which requires disabling interrupts */ /* Protecting only lru_rotate.fbatch which requires disabling interrupts */
struct lru_rotate { struct lru_rotate {