From ea0ffd0c08d0fef1f6e93eb07badbeeabf6b43d6 Mon Sep 17 00:00:00 2001 From: Kairui Song Date: Mon, 24 Oct 2022 00:25:33 +0800 Subject: [PATCH] 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: Kairui Song Signed-off-by: Andrew Morton --- include/linux/mm.h | 1 + kernel/sysctl.c | 1 + mm/swap.c | 3 ++- 3 files changed, 4 insertions(+), 1 deletion(-) diff --git a/include/linux/mm.h b/include/linux/mm.h index 429ff89bfe06..255931ebf2dc 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -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; diff --git a/kernel/sysctl.c b/kernel/sysctl.c index 188c305aeb8b..71a4350ac601 100644 --- a/kernel/sysctl.c +++ b/kernel/sysctl.c @@ -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", diff --git a/mm/swap.c b/mm/swap.c index 2f12a2ee1d3a..b9a6817e07ff 100644 --- a/mm/swap.c +++ b/mm/swap.c @@ -43,8 +43,9 @@ #define CREATE_TRACE_POINTS #include -/* 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 {