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signal: make oom_flags a bool

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Currently the size of "struct signal_struct"->oom_flags member is
sizeof(unsigned) bytes, but only one flag OOM_FLAG_ORIGIN which is
updated by current thread is defined.  We can convert OOM_FLAG_ORIGIN
into a bool, and reuse the saved bytes for updating from the OOM killer
and/or the OOM reaper thread.

By the way, do we care about a race window between run_store() and
swapoff() because it would be theoretically possible that two threads
sharing the "struct signal_struct" concurrently call respective
functions? If we care, we can make oom_flags an atomic_t.

Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Cc: Hugh Dickins <hughd@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Tetsuo Handa 2016-05-23 16:23:57 -07:00 committed by Linus Torvalds
parent 91c4e8ea8f
commit c96fc2d85f
3 changed files with 8 additions and 8 deletions
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9
include/linux/oom.h
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@ -50,24 +50,21 @@ enum oom_scan_t {
OOM_SCAN_SELECT, /* always select this thread first */
};
/* Thread is the potential origin of an oom condition; kill first on oom */
#define OOM_FLAG_ORIGIN ((__force oom_flags_t)0x1)
extern struct mutex oom_lock;
static inline void set_current_oom_origin(void)
{
current->signal->oom_flags |= OOM_FLAG_ORIGIN;
current->signal->oom_flag_origin = true;
}
static inline void clear_current_oom_origin(void)
{
current->signal->oom_flags &= ~OOM_FLAG_ORIGIN;
current->signal->oom_flag_origin = false;
}
static inline bool oom_task_origin(const struct task_struct *p)
{
return !!(p->signal->oom_flags & OOM_FLAG_ORIGIN);
return p->signal->oom_flag_origin;
}
extern void mark_oom_victim(struct task_struct *tsk);

6
include/linux/sched.h
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@ -794,7 +794,11 @@ struct signal_struct {
struct tty_audit_buf *tty_audit_buf;
#endif
oom_flags_t oom_flags;
/*
* Thread is the potential origin of an oom condition; kill first on
* oom
*/
bool oom_flag_origin;
short oom_score_adj; /* OOM kill score adjustment */
short oom_score_adj_min; /* OOM kill score adjustment min value.
* Only settable by CAP_SYS_RESOURCE. */

1
include/linux/types.h
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@ -156,7 +156,6 @@ typedef u32 dma_addr_t;
typedef unsigned __bitwise__ gfp_t;
typedef unsigned __bitwise__ fmode_t;
typedef unsigned __bitwise__ oom_flags_t;
#ifdef CONFIG_PHYS_ADDR_T_64BIT
typedef u64 phys_addr_t;