The patch titled
Subject: frontswap: get rid of swap_lock dependency
has been removed from the -mm tree. Its filename was
frontswap-get-rid-of-swap_lock-dependency.patch
This patch was dropped because it was merged into mainline or a subsystem tree
------------------------------------------------------
From: Minchan Kim <minchan@xxxxxxxxxx>
Subject: frontswap: get rid of swap_lock dependency
Frontswap initialization routine depends on swap_lock, which want to be
atomic about frontswap's first appearance. IOW, frontswap is not present
and will fail all calls OR frontswap is fully functional but if new
swap_info_struct isn't registered by enable_swap_info, swap subsystem
doesn't start I/O so there is no race between init procedure and page I/O
working on frontswap.
So let's remove unnecessary swap_lock dependency.
Cc: Dan Magenheimer <dan.magenheimer@xxxxxxxxxx>
Signed-off-by: Minchan Kim <minchan@xxxxxxxxxx>
[v1: Rebased on my branch, reworked to work with backends loading late]
[v2: Added a check for !map]
[v3: Made the invalidate path follow the init path]
[v4: Address comments by Wanpeng Li <liwanp@xxxxxxxxxxxxxxxxxx>]
Signed-off-by: Konrad Rzeszutek Wilk <konrad@xxxxxxxxxx>
Signed-off-by: Bob Liu <lliubbo@xxxxxxxxx>
Cc: Wanpeng Li <liwanp@xxxxxxxxxxxxxxxxxx>
Cc: Andor Daam <andor.daam@xxxxxxxxxxxxxx>
Cc: Florian Schmaus <fschmaus@xxxxxxxxx>
Cc: Stefan Hengelein <ilendir@xxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
include/linux/frontswap.h | 6 +++---
mm/frontswap.c | 31 +++++++++++++++++++++++--------
mm/swapfile.c | 17 +++++++++--------
3 files changed, 35 insertions(+), 19 deletions(-)
diff -puN include/linux/frontswap.h~frontswap-get-rid-of-swap_lock-dependency include/linux/frontswap.h
--- a/include/linux/frontswap.h~frontswap-get-rid-of-swap_lock-dependency
+++ a/include/linux/frontswap.h
@@ -23,7 +23,7 @@ extern void frontswap_writethrough(bool)
extern void frontswap_tmem_exclusive_gets(bool);
extern bool __frontswap_test(struct swap_info_struct *, pgoff_t);
-extern void __frontswap_init(unsigned type);
+extern void __frontswap_init(unsigned type, unsigned long *map);
extern int __frontswap_store(struct page *page);
extern int __frontswap_load(struct page *page);
extern void __frontswap_invalidate_page(unsigned, pgoff_t);
@@ -98,10 +98,10 @@ static inline void frontswap_invalidate_
__frontswap_invalidate_area(type);
}
-static inline void frontswap_init(unsigned type)
+static inline void frontswap_init(unsigned type, unsigned long *map)
{
if (frontswap_enabled)
- __frontswap_init(type);
+ __frontswap_init(type, map);
}
#endif /* _LINUX_FRONTSWAP_H */
diff -puN mm/frontswap.c~frontswap-get-rid-of-swap_lock-dependency mm/frontswap.c
--- a/mm/frontswap.c~frontswap-get-rid-of-swap_lock-dependency
+++ a/mm/frontswap.c
@@ -121,8 +121,13 @@ struct frontswap_ops *frontswap_register
int i;
for (i = 0; i < MAX_SWAPFILES; i++) {
- if (test_and_clear_bit(i, need_init))
+ if (test_and_clear_bit(i, need_init)) {
+ struct swap_info_struct *sis = swap_info[i];
+ /* __frontswap_init _should_ have set it! */
+ if (!sis->frontswap_map)
+ return ERR_PTR(-EINVAL);
ops->init(i);
+ }
}
/*
* We MUST have frontswap_ops set _after_ the frontswap_init's
@@ -156,20 +161,30 @@ EXPORT_SYMBOL(frontswap_tmem_exclusive_g
/*
* Called when a swap device is swapon'd.
*/
-void __frontswap_init(unsigned type)
+void __frontswap_init(unsigned type, unsigned long *map)
{
struct swap_info_struct *sis = swap_info[type];
- if (frontswap_ops) {
- BUG_ON(sis == NULL);
- if (sis->frontswap_map == NULL)
- return;
+ BUG_ON(sis == NULL);
+
+ /*
+ * p->frontswap is a bitmap that we MUST have to figure out which page
+ * has gone in frontswap. Without it there is no point of continuing.
+ */
+ if (WARN_ON(!map))
+ return;
+ /*
+ * Irregardless of whether the frontswap backend has been loaded
+ * before this function or it will be later, we _MUST_ have the
+ * p->frontswap set to something valid to work properly.
+ */
+ frontswap_map_set(sis, map);
+ if (frontswap_ops)
frontswap_ops->init(type);
- } else {
+ else {
BUG_ON(type > MAX_SWAPFILES);
set_bit(type, need_init);
}
-
}
EXPORT_SYMBOL(__frontswap_init);
diff -puN mm/swapfile.c~frontswap-get-rid-of-swap_lock-dependency mm/swapfile.c
--- a/mm/swapfile.c~frontswap-get-rid-of-swap_lock-dependency
+++ a/mm/swapfile.c
@@ -1509,8 +1509,7 @@ static int setup_swap_extents(struct swa
}
static void _enable_swap_info(struct swap_info_struct *p, int prio,
- unsigned char *swap_map,
- unsigned long *frontswap_map)
+ unsigned char *swap_map)
{
int i, prev;
@@ -1519,7 +1518,6 @@ static void _enable_swap_info(struct swa
else
p->prio = --least_priority;
p->swap_map = swap_map;
- frontswap_map_set(p, frontswap_map);
p->flags |= SWP_WRITEOK;
atomic_long_add(p->pages, &nr_swap_pages);
total_swap_pages += p->pages;
@@ -1542,10 +1540,10 @@ static void enable_swap_info(struct swap
unsigned char *swap_map,
unsigned long *frontswap_map)
{
+ frontswap_init(p->type, frontswap_map);
spin_lock(&swap_lock);
spin_lock(&p->lock);
- _enable_swap_info(p, prio, swap_map, frontswap_map);
- frontswap_init(p->type);
+ _enable_swap_info(p, prio, swap_map);
spin_unlock(&p->lock);
spin_unlock(&swap_lock);
}
@@ -1554,7 +1552,7 @@ static void reinsert_swap_info(struct sw
{
spin_lock(&swap_lock);
spin_lock(&p->lock);
- _enable_swap_info(p, p->prio, p->swap_map, frontswap_map_get(p));
+ _enable_swap_info(p, p->prio, p->swap_map);
spin_unlock(&p->lock);
spin_unlock(&swap_lock);
}
@@ -1563,6 +1561,7 @@ SYSCALL_DEFINE1(swapoff, const char __us
{
struct swap_info_struct *p = NULL;
unsigned char *swap_map;
+ unsigned long *frontswap_map;
struct file *swap_file, *victim;
struct address_space *mapping;
struct inode *inode;
@@ -1662,12 +1661,14 @@ SYSCALL_DEFINE1(swapoff, const char __us
swap_map = p->swap_map;
p->swap_map = NULL;
p->flags = 0;
- frontswap_invalidate_area(type);
+ frontswap_map = frontswap_map_get(p);
+ frontswap_map_set(p, NULL);
spin_unlock(&p->lock);
spin_unlock(&swap_lock);
+ frontswap_invalidate_area(type);
mutex_unlock(&swapon_mutex);
vfree(swap_map);
- vfree(frontswap_map_get(p));
+ vfree(frontswap_map);
/* Destroy swap account informatin */
swap_cgroup_swapoff(type);
_
Patches currently in -mm which might be from minchan@xxxxxxxxxx are
origin.patch
mm-add-vm-event-counters-for-balloon-pages-compaction.patch
block-aio-batch-completion-for-bios-kiocbs.patch
debugging-keep-track-of-page-owners-fix-2.patch
debugging-keep-track-of-page-owners-fix-2-fix.patch
debugging-keep-track-of-page-owners-fix-2-fix-fix.patch
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