The counter of free swap turn to negtive during swapoff, this
phenomenon can be observed in oom log, such as:
1226 total pagecache pages
47 pages in swap cache
Swap cache stats: add 119633, delete 119814, find 26832/82125
Free swap = -31796kB
Total swap = 0kB
1048576 pages RAM
Subtract the size of swap partition from free swap should put behind
try_to_unuse, otherwise, it will result in negtive counter if swap
partition is in use.
Fixes: ec8acf20afb8 ("swap: add per-partition lock for swapfile")
Signed-off-by: Chen Wandun <chenwandun@xxxxxxxxxx>
---
mm/swapfile.c | 8 ++++----
1 file changed, 4 insertions(+), 4 deletions(-)
diff --git a/mm/swapfile.c b/mm/swapfile.c
index 72e481aacd5d..5b9b695be84b 100644
--- a/mm/swapfile.c
+++ b/mm/swapfile.c
@@ -2316,8 +2316,6 @@ static void setup_swap_info(struct swap_info_struct *p, int prio,
static void _enable_swap_info(struct swap_info_struct *p)
{
p->flags |= SWP_WRITEOK;
- atomic_long_add(p->pages, &nr_swap_pages);
- total_swap_pages += p->pages;
assert_spin_locked(&swap_lock);
/*
@@ -2353,6 +2351,8 @@ static void enable_swap_info(struct swap_info_struct *p, int prio,
spin_lock(&swap_lock);
spin_lock(&p->lock);
_enable_swap_info(p);
+ atomic_long_add(p->pages, &nr_swap_pages);
+ total_swap_pages += p->pages;
spin_unlock(&p->lock);
spin_unlock(&swap_lock);
}
@@ -2444,8 +2444,6 @@ SYSCALL_DEFINE1(swapoff, const char __user *, specialfile)
least_priority++;
}
plist_del(&p->list, &swap_active_head);
- atomic_long_sub(p->pages, &nr_swap_pages);
- total_swap_pages -= p->pages;
p->flags &= ~SWP_WRITEOK;
spin_unlock(&p->lock);
spin_unlock(&swap_lock);
@@ -2500,6 +2498,8 @@ SYSCALL_DEFINE1(swapoff, const char __user *, specialfile)
spin_lock(&p->lock);
}
+ atomic_long_sub(p->pages, &nr_swap_pages);
+ total_swap_pages -= p->pages;
swap_file = p->swap_file;
old_block_size = p->old_block_size;
p->swap_file = NULL;
--
2.25.1
