[PATCH -mm] mm, swap: Fix false error message in __swp_swapcount()
From: Huang, Ying <hidden>
Date: 2017-10-24 02:47:29
Also in:
linux-mm, lkml
Subsystem:
memory management, memory management - swap, the rest · Maintainers:
Andrew Morton, Chris Li, Kairui Song, Linus Torvalds
From: Ying Huang <redacted>
__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 <redacted>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: <redacted> # 4.11-4.13
Reported-by: Christian Kujau <redacted>
Fixes: e8c26ab60598 ("mm/swap: skip readahead for unreferenced swap slots")
Signed-off-by: "Huang, Ying" <redacted>
---
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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