[PATCH v8 4/4] mm/madvise: check fatal signal pending of target process

Minchan Kim
2020-06-22T19:29:36Z

Bail out to prevent unnecessary CPU overhead if target process has pending
fatal signal during (MADV_COLD|MADV_PAGEOUT) operation.

Link: http://lkml.kernel.org/r/20200302193630.68771-4-minchan@kernel.org
Signed-off-by: Minchan Kim <minchan@kernel.org>
Reviewed-by: Suren Baghdasaryan <surenb@google.com>
Reviewed-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Alexander Duyck <alexander.h.duyck@linux.intel.com>
Cc: Brian Geffon <bgeffon@google.com>
Cc: Christian Brauner <christian@brauner.io>
Cc: Daniel Colascione <dancol@google.com>
Cc: Jann Horn <jannh@google.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Joel Fernandes <joel@joelfernandes.org>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: John Dias <joaodias@google.com>
Cc: Kirill Tkhai <ktkhai@virtuozzo.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Oleksandr Natalenko <oleksandr@redhat.com>
Cc: Sandeep Patil <sspatil@google.com>
Cc: SeongJae Park <sj38.park@gmail.com>
Cc: SeongJae Park <sjpark@amazon.de>
Cc: Shakeel Butt <shakeelb@google.com>
Cc: Sonny Rao <sonnyrao@google.com>
Cc: Tim Murray <timmurray@google.com>
Cc: Christian Brauner <christian.brauner@ubuntu.com>
Cc: <linux-man@vger.kernel.org>
---
mm/madvise.c | 29 +++++++++++++++++++++--------
1 file changed, 21 insertions(+), 8 deletions(-)

diff --git a/mm/madvise.c b/mm/madvise.c
index 23abca3f93fa..a16dba21cdf6 100644
--- a/mm/madvise.c
+++ b/mm/madvise.c
@@ -39,6 +39,7 @@
struct madvise_walk_private {
struct mmu_gather *tlb;
bool pageout;
+ struct task_struct *target_task;
};

/*
@@ -319,6 +320,10 @@ static int madvise_cold_or_pageout_pte_range(pmd_t *pmd,
if (fatal_signal_pending(current))
return -EINTR;

+ if (private->target_task &&
+ fatal_signal_pending(private->target_task))
+ return -EINTR;
+
#ifdef CONFIG_TRANSPARENT_HUGEPAGE
if (pmd_trans_huge(*pmd)) {
pmd_t orig_pmd;
@@ -480,12 +485,14 @@ static const struct mm_walk_ops cold_walk_ops = {
};

static void madvise_cold_page_range(struct mmu_gather *tlb,
+ struct task_struct *task,
struct vm_area_struct *vma,
unsigned long addr, unsigned long end)
{
struct madvise_walk_private walk_private = {
.pageout = false,
.tlb = tlb,
+ .target_task = task,
};

tlb_start_vma(tlb, vma);
@@ -493,7 +500,8 @@ static void madvise_cold_page_range(struct mmu_gather *tlb,
tlb_end_vma(tlb, vma);
}

-static long madvise_cold(struct vm_area_struct *vma,
+static long madvise_cold(struct task_struct *task,
+ struct vm_area_struct *vma,
struct vm_area_struct **prev,
unsigned long start_addr, unsigned long end_addr)
{
@@ -506,19 +514,21 @@ static long madvise_cold(struct vm_area_struct *vma,

lru_add_drain();
tlb_gather_mmu(&tlb, mm, start_addr, end_addr);
- madvise_cold_page_range(&tlb, vma, start_addr, end_addr);
+ madvise_cold_page_range(&tlb, task, vma, start_addr, end_addr);
tlb_finish_mmu(&tlb, start_addr, end_addr);

return 0;
}

static void madvise_pageout_page_range(struct mmu_gather *tlb,
+ struct task_struct *task,
struct vm_area_struct *vma,
unsigned long addr, unsigned long end)
{
struct madvise_walk_private walk_private = {
.pageout = true,
.tlb = tlb,
+ .target_task = task,
};

tlb_start_vma(tlb, vma);
@@ -542,7 +552,8 @@ static inline bool can_do_pageout(struct vm_area_struct *vma)
inode_permission(file_inode(vma->vm_file), MAY_WRITE) == 0;
}

-static long madvise_pageout(struct vm_area_struct *vma,
+static long madvise_pageout(struct task_struct *task,
+ struct vm_area_struct *vma,
struct vm_area_struct **prev,
unsigned long start_addr, unsigned long end_addr)
{
@@ -558,7 +569,7 @@ static long madvise_pageout(struct vm_area_struct *vma,

lru_add_drain();
tlb_gather_mmu(&tlb, mm, start_addr, end_addr);
- madvise_pageout_page_range(&tlb, vma, start_addr, end_addr);
+ madvise_pageout_page_range(&tlb, task, vma, start_addr, end_addr);
tlb_finish_mmu(&tlb, start_addr, end_addr);

return 0;
@@ -938,7 +949,8 @@ static int madvise_inject_error(int behavior,
#endif

static long
-madvise_vma(struct vm_area_struct *vma, struct vm_area_struct **prev,
+madvise_vma(struct task_struct *task, struct vm_area_struct *vma,
+ struct vm_area_struct **prev,
unsigned long start, unsigned long end, int behavior)
{
switch (behavior) {
@@ -947,9 +959,9 @@ madvise_vma(struct vm_area_struct *vma, struct vm_area_struct **prev,
case MADV_WILLNEED:
return madvise_willneed(vma, prev, start, end);
case MADV_COLD:
- return madvise_cold(vma, prev, start, end);
+ return madvise_cold(task, vma, prev, start, end);
case MADV_PAGEOUT:
- return madvise_pageout(vma, prev, start, end);
+ return madvise_pageout(task, vma, prev, start, end);
case MADV_FREE:
case MADV_DONTNEED:
return madvise_dontneed_free(vma, prev, start, end, behavior);
@@ -1166,7 +1178,8 @@ int do_madvise(struct task_struct *target_task, struct mm_struct *mm,
tmp = end;

/* Here vma->vm_start <= start < tmp <= (end|vma->vm_end). */
- error = madvise_vma(vma, &prev, start, tmp, behavior);
+ error = madvise_vma(target_task, vma, &prev,
+ start, tmp, behavior);
if (error)
goto out;
start = tmp;
--
2.27.0.111.gc72c7da667-goog