Commit ea0ffd0c authored by Kairui Song's avatar Kairui Song Committed by Andrew Morton
Browse files

swap: add a limit for readahead page-cluster value 

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: default avatarKairui Song <kasong@tencent.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
parent 5033091d

include/linux/mm.h

+1 −0
Original line number Diff line number Diff line
@@ -74,6 +74,7 @@ static inline void totalram_pages_add(long count) 


extern void * high_memory;

extern int page_cluster;

extern const int page_cluster_max;



#ifdef CONFIG_SYSCTL

extern int sysctl_legacy_va_layout;

kernel/sysctl.c

+1 −0
Original line number Diff line number Diff line
@@ -2125,6 +2125,7 @@ static struct ctl_table vm_table[] = { 
		.mode		= 0644,

		.proc_handler	= proc_dointvec_minmax,

		.extra1		= SYSCTL_ZERO,

		.extra2		= (void *)&page_cluster_max,

	},

	{

		.procname	= "dirtytime_expire_seconds",

mm/swap.c

+2 −1
Original line number Diff line number Diff line
@@ -43,8 +43,9 @@ 
#define CREATE_TRACE_POINTS

#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;

const int page_cluster_max = 31;



/* Protecting only lru_rotate.fbatch which requires disabling interrupts */

struct lru_rotate {