evie/android_kernel_oneplus_msm8998
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ANDROID: Fixes to locking around handle_lmk_event

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get_task_struct used to reserve 'selected' outside rcu_read_lock block.
Remove the need for get_task_mm, removing the possibility of lock issues there.

Bug: 133479338
Signed-off-by: Jim Blackler <jimblackler@google.com>
Change-Id: I1399e2f669242c04e0e397bc09c987358aa97a0a
This commit is contained in:
Jim Blackler 2019-07-03 17:33:51 +01:00
parent c93a1fab24
commit d657433f12
1 changed files with 8 additions and 12 deletions
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20
drivers/staging/android/lowmemorykiller.c
View file

@ -94,21 +94,15 @@ struct lmk_event {
struct list_head list;
};
void handle_lmk_event(struct task_struct *selected, short min_score_adj)
void handle_lmk_event(struct task_struct *selected, int selected_tasksize,
short min_score_adj)
{
int head;
int tail;
struct lmk_event *events;
struct lmk_event *event;
int res;
long rss_in_pages = -1;
char taskname[MAX_TASKNAME];
struct mm_struct *mm = get_task_mm(selected);
if (mm) {
rss_in_pages = get_mm_rss(mm);
mmput(mm);
}
res = get_cmdline(selected, taskname, MAX_TASKNAME - 1);
@ -147,7 +141,7 @@ void handle_lmk_event(struct task_struct *selected, short min_score_adj)
event->maj_flt = selected->maj_flt;
event->oom_score_adj = selected->signal->oom_score_adj;
event->start_time = nsec_to_clock_t(selected->real_start_time);
event->rss_in_pages = rss_in_pages;
event->rss_in_pages = selected_tasksize;
event->min_score_adj = min_score_adj;
event_buffer.head = (head + 1) & (MAX_BUFFERED_EVENTS - 1);
@ -346,15 +340,17 @@ static unsigned long lowmem_scan(struct shrinker *s, struct shrink_control *sc)
free);
lowmem_deathpending_timeout = jiffies + HZ;
rem += selected_tasksize;
get_task_struct(selected);
}
lowmem_print(4, "lowmem_scan %lu, %x, return %lu\n",
sc->nr_to_scan, sc->gfp_mask, rem);
rcu_read_unlock();
if (selected)
handle_lmk_event(selected, min_score_adj);
if (selected) {
handle_lmk_event(selected, selected_tasksize, min_score_adj);
put_task_struct(selected);
}
return rem;
}