From: Ying Huang <ying.huang@xxxxxxxxx>
__swp_swapcount() is used in __read_swap_cache_async(). Where the
invalid swap entry (offset > max) may be supplied during swap
readahead. But __swp_swapcount() will print error message for these
expected invalid swap entry as below, which will make the users
confusing.
swap_info_get: Bad swap offset entry 0200f8a7
So the swap entry checking code in __swp_swapcount() is changed to
avoid printing error message for it. To avoid to duplicate code with
__swap_duplicate(), a new helper function named
__swap_info_get_silence() is added and invoked in both places.
Cc: Tim Chen <tim.c.chen@xxxxxxxxxxxxxxx>
Cc: Minchan Kim <minchan@xxxxxxxxxx>
Cc: Michal Hocko <mhocko@xxxxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx> # 4.11-4.13
Reported-by: Christian Kujau <lists@xxxxxxxxxxxxxxx>
Fixes: e8c26ab60598 ("mm/swap: skip readahead for unreferenced swap slots")
Signed-off-by: "Huang, Ying" <ying.huang@xxxxxxxxx>
---
mm/swapfile.c | 42 ++++++++++++++++++++++++++++--------------
1 file changed, 28 insertions(+), 14 deletions(-)
diff --git a/mm/swapfile.c b/mm/swapfile.c
index 3074b02eaa09..3193aa670c90 100644
--- a/mm/swapfile.c
+++ b/mm/swapfile.c
@@ -1107,6 +1107,30 @@ static struct swap_info_struct *swap_info_get_cont(swp_entry_t entry,
return p;
}
+static struct swap_info_struct *__swap_info_get_silence(swp_entry_t entry)
+{
+ struct swap_info_struct *p;
+ unsigned long offset, type;
+
+ if (non_swap_entry(entry))
+ goto out;
+
+ type = swp_type(entry);
+ if (type >= nr_swapfiles)
+ goto bad_file;
+ p = swap_info[type];
+ offset = swp_offset(entry);
+ if (unlikely(offset >= p->max))
+ goto out;
+
+ return p;
+
+bad_file:
+ pr_err("swap_info_get_silence: %s%08lx\n", Bad_file, entry.val);
+out:
+ return NULL;
+}
+
static unsigned char __swap_entry_free(struct swap_info_struct *p,
swp_entry_t entry, unsigned char usage)
{
@@ -1357,7 +1381,7 @@ int __swp_swapcount(swp_entry_t entry)
int count = 0;
struct swap_info_struct *si;
- si = __swap_info_get(entry);
+ si = __swap_info_get_silence(entry);
if (si)
count = swap_swapcount(si, entry);
return count;
@@ -3356,22 +3380,16 @@ static int __swap_duplicate(swp_entry_t entry, unsigned char usage)
{
struct swap_info_struct *p;
struct swap_cluster_info *ci;
- unsigned long offset, type;
+ unsigned long offset;
unsigned char count;
unsigned char has_cache;
int err = -EINVAL;
- if (non_swap_entry(entry))
+ p = __swap_info_get_silence(entry);
+ if (!p)
goto out;
- type = swp_type(entry);
- if (type >= nr_swapfiles)
- goto bad_file;
- p = swap_info[type];
offset = swp_offset(entry);
- if (unlikely(offset >= p->max))
- goto out;
-
ci = lock_cluster_or_swap_info(p, offset);
count = p->swap_map[offset];
@@ -3418,10 +3436,6 @@ static int __swap_duplicate(swp_entry_t entry, unsigned char usage)
unlock_cluster_or_swap_info(p, ci);
out:
return err;
-
-bad_file:
- pr_err("swap_dup: %s%08lx\n", Bad_file, entry.val);
- goto out;
}
/*
--
2.14.2
--
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