The patch titled
mm: fix page-faults detection in swap-token logic
has been added to the -mm tree. Its filename is
mm-fix-page-faults-detection-in-swap-token-logic.patch
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------------------------------------------------------
Subject: mm: fix page-faults detection in swap-token logic
From: Konstantin Khlebnikov <khlebnikov@xxxxxxxxxx>
After commit v2.6.36-5896-gd065bd8 "mm: retry page fault when blocking on
disk transfer" we usually wait in page-faults without mmap_sem held, so
all swap-token logic was broken, because it based on using
rwsem_is_locked(&mm->mmap_sem) as sign of in progress page-faults.
Add an atomic counter of in progress page-faults for mm to the mm_struct
with swap-token.
Signed-off-by: Konstantin Khlebnikov <khlebnikov@xxxxxxxxxx>
Cc: Rik van Riel <riel@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
include/linux/mm_types.h | 1 +
include/linux/swap.h | 34 ++++++++++++++++++++++++++++++++++
kernel/fork.c | 1 +
mm/memory.c | 13 +++++++++++++
mm/rmap.c | 3 +--
5 files changed, 50 insertions(+), 2 deletions(-)
diff -puN include/linux/mm_types.h~mm-fix-page-faults-detection-in-swap-token-logic include/linux/mm_types.h
--- a/include/linux/mm_types.h~mm-fix-page-faults-detection-in-swap-token-logic
+++ a/include/linux/mm_types.h
@@ -331,6 +331,7 @@ struct mm_struct {
unsigned int faultstamp;
unsigned int token_priority;
unsigned int last_interval;
+ atomic_t active_swap_token;
/* How many tasks sharing this mm are OOM_DISABLE */
atomic_t oom_disable_count;
diff -puN include/linux/swap.h~mm-fix-page-faults-detection-in-swap-token-logic include/linux/swap.h
--- a/include/linux/swap.h~mm-fix-page-faults-detection-in-swap-token-logic
+++ a/include/linux/swap.h
@@ -357,6 +357,26 @@ static inline void put_swap_token(struct
__put_swap_token(mm);
}
+static inline bool has_active_swap_token(struct mm_struct *mm)
+{
+ return has_swap_token(mm) && atomic_read(&mm->active_swap_token);
+}
+
+static inline bool activate_swap_token(struct mm_struct *mm)
+{
+ if (has_swap_token(mm)) {
+ atomic_inc(&mm->active_swap_token);
+ return true;
+ }
+ return false;
+}
+
+static inline void deactivate_swap_token(struct mm_struct *mm, bool swap_token)
+{
+ if (swap_token)
+ atomic_dec(&mm->active_swap_token);
+}
+
#ifdef CONFIG_CGROUP_MEM_RES_CTLR
extern void
mem_cgroup_uncharge_swapcache(struct page *page, swp_entry_t ent, bool swapout);
@@ -482,6 +502,20 @@ static inline int has_swap_token(struct
return 0;
}
+static inline bool has_active_swap_token(struct mm_struct *mm)
+{
+ return false;
+}
+
+static inline bool activate_swap_token(struct mm_struct *mm)
+{
+ return false;
+}
+
+static inline void deactivate_swap_token(struct mm_struct *mm, bool swap_token)
+{
+}
+
static inline void disable_swap_token(struct mem_cgroup *memcg)
{
}
diff -puN kernel/fork.c~mm-fix-page-faults-detection-in-swap-token-logic kernel/fork.c
--- a/kernel/fork.c~mm-fix-page-faults-detection-in-swap-token-logic
+++ a/kernel/fork.c
@@ -764,6 +764,7 @@ struct mm_struct *dup_mm(struct task_str
/* Initializing for Swap token stuff */
mm->token_priority = 0;
mm->last_interval = 0;
+ atomic_set(&mm->active_swap_token, 0);
#ifdef CONFIG_TRANSPARENT_HUGEPAGE
mm->pmd_huge_pte = NULL;
diff -puN mm/memory.c~mm-fix-page-faults-detection-in-swap-token-logic mm/memory.c
--- a/mm/memory.c~mm-fix-page-faults-detection-in-swap-token-logic
+++ a/mm/memory.c
@@ -2861,6 +2861,7 @@ static int do_swap_page(struct mm_struct
struct mem_cgroup *ptr;
int exclusive = 0;
int ret = 0;
+ bool swap_token;
if (!pte_unmap_same(mm, pmd, page_table, orig_pte))
goto out;
@@ -2909,7 +2910,12 @@ static int do_swap_page(struct mm_struct
goto out_release;
}
+ swap_token = activate_swap_token(mm);
+
locked = lock_page_or_retry(page, mm, flags);
+
+ deactivate_swap_token(mm, swap_token);
+
delayacct_clear_flag(DELAYACCT_PF_SWAPIN);
if (!locked) {
ret |= VM_FAULT_RETRY;
@@ -3156,6 +3162,7 @@ static int __do_fault(struct mm_struct *
struct vm_fault vmf;
int ret;
int page_mkwrite = 0;
+ bool swap_token;
/*
* If we do COW later, allocate page befor taking lock_page()
@@ -3177,6 +3184,8 @@ static int __do_fault(struct mm_struct *
} else
cow_page = NULL;
+ swap_token = activate_swap_token(mm);
+
vmf.virtual_address = (void __user *)(address & PAGE_MASK);
vmf.pgoff = pgoff;
vmf.flags = flags;
@@ -3245,6 +3254,8 @@ static int __do_fault(struct mm_struct *
}
+ deactivate_swap_token(mm, swap_token);
+
page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
/*
@@ -3316,9 +3327,11 @@ static int __do_fault(struct mm_struct *
return ret;
unwritable_page:
+ deactivate_swap_token(mm, swap_token);
page_cache_release(page);
return ret;
uncharge_out:
+ deactivate_swap_token(mm, swap_token);
/* fs's fault handler get error */
if (cow_page) {
mem_cgroup_uncharge_page(cow_page);
diff -puN mm/rmap.c~mm-fix-page-faults-detection-in-swap-token-logic mm/rmap.c
--- a/mm/rmap.c~mm-fix-page-faults-detection-in-swap-token-logic
+++ a/mm/rmap.c
@@ -715,8 +715,7 @@ int page_referenced_one(struct page *pag
/* Pretend the page is referenced if the task has the
swap token and is in the middle of a page fault. */
- if (mm != current->mm && has_swap_token(mm) &&
- rwsem_is_locked(&mm->mmap_sem))
+ if (mm != current->mm && has_active_swap_token(mm))
referenced++;
(*mapcount)--;
_
Patches currently in -mm which might be from khlebnikov@xxxxxxxxxx are
linux-next.patch
vmscan-fix-initial-shrinker-size-handling.patch
vmscan-use-atomic-long-for-shrinker-batching.patch
vmscan-use-atomic-long-for-shrinker-batching-fix.patch
vmscan-promote-shared-file-mapped-pages.patch
vmscan-activate-executable-pages-after-first-usage.patch
mm-add-free_hot_cold_page_list-helper.patch
mm-fix-page-faults-detection-in-swap-token-logic.patch
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