From 72788c385604523422592249c19cba0187021e9b Mon Sep 17 00:00:00 2001 From: David Rientjes Date: Tue, 24 May 2011 17:11:40 -0700 Subject: [PATCH] oom: replace PF_OOM_ORIGIN with toggling oom_score_adj There's a kernel-wide shortage of per-process flags, so it's always helpful to trim one when possible without incurring a significant penalty. It's even more important when you're planning on adding a per- process flag yourself, which I plan to do shortly for transparent hugepages. PF_OOM_ORIGIN is used by ksm and swapoff to prefer current since it has a tendency to allocate large amounts of memory and should be preferred for killing over other tasks. We'd rather immediately kill the task making the errant syscall rather than penalizing an innocent task. This patch removes PF_OOM_ORIGIN since its behavior is equivalent to setting the process's oom_score_adj to OOM_SCORE_ADJ_MAX. The process's old oom_score_adj is stored and then set to OOM_SCORE_ADJ_MAX during the time it used to have PF_OOM_ORIGIN. The old value is then reinstated when the process should no longer be considered a high priority for oom killing. Signed-off-by: David Rientjes Reviewed-by: KOSAKI Motohiro Reviewed-by: Minchan Kim Cc: Hugh Dickins Cc: Izik Eidus Cc: KAMEZAWA Hiroyuki Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- include/linux/oom.h | 2 ++ include/linux/sched.h | 1 - mm/ksm.c | 7 +++++-- mm/oom_kill.c | 36 +++++++++++++++++++++++++++--------- mm/swapfile.c | 6 ++++-- 5 files changed, 38 insertions(+), 14 deletions(-) diff --git a/include/linux/oom.h b/include/linux/oom.h index 5e3aa8311c5e..4952fb874ad3 100644 --- a/include/linux/oom.h +++ b/include/linux/oom.h @@ -40,6 +40,8 @@ enum oom_constraint { CONSTRAINT_MEMCG, }; +extern int test_set_oom_score_adj(int new_val); + extern unsigned int oom_badness(struct task_struct *p, struct mem_cgroup *mem, const nodemask_t *nodemask, unsigned long totalpages); extern int try_set_zonelist_oom(struct zonelist *zonelist, gfp_t gfp_flags); diff --git a/include/linux/sched.h b/include/linux/sched.h index aaf71e08222c..44b8faaac7c0 100644 --- a/include/linux/sched.h +++ b/include/linux/sched.h @@ -1753,7 +1753,6 @@ extern void thread_group_times(struct task_struct *p, cputime_t *ut, cputime_t * #define PF_FROZEN 0x00010000 /* frozen for system suspend */ #define PF_FSTRANS 0x00020000 /* inside a filesystem transaction */ #define PF_KSWAPD 0x00040000 /* I am kswapd */ -#define PF_OOM_ORIGIN 0x00080000 /* Allocating much memory to others */ #define PF_LESS_THROTTLE 0x00100000 /* Throttle me less: I clean memory */ #define PF_KTHREAD 0x00200000 /* I am a kernel thread */ #define PF_RANDOMIZE 0x00400000 /* randomize virtual address space */ diff --git a/mm/ksm.c b/mm/ksm.c index 942dfc73a2ff..d708b3ef2260 100644 --- a/mm/ksm.c +++ b/mm/ksm.c @@ -35,6 +35,7 @@ #include #include #include +#include #include #include "internal.h" @@ -1894,9 +1895,11 @@ static ssize_t run_store(struct kobject *kobj, struct kobj_attribute *attr, if (ksm_run != flags) { ksm_run = flags; if (flags & KSM_RUN_UNMERGE) { - current->flags |= PF_OOM_ORIGIN; + int oom_score_adj; + + oom_score_adj = test_set_oom_score_adj(OOM_SCORE_ADJ_MAX); err = unmerge_and_remove_all_rmap_items(); - current->flags &= ~PF_OOM_ORIGIN; + test_set_oom_score_adj(oom_score_adj); if (err) { ksm_run = KSM_RUN_STOP; count = err; diff --git a/mm/oom_kill.c b/mm/oom_kill.c index f52e85c80e8d..e4b0991ca351 100644 --- a/mm/oom_kill.c +++ b/mm/oom_kill.c @@ -38,6 +38,33 @@ int sysctl_oom_kill_allocating_task; int sysctl_oom_dump_tasks = 1; static DEFINE_SPINLOCK(zone_scan_lock); +/** + * test_set_oom_score_adj() - set current's oom_score_adj and return old value + * @new_val: new oom_score_adj value + * + * Sets the oom_score_adj value for current to @new_val with proper + * synchronization and returns the old value. Usually used to temporarily + * set a value, save the old value in the caller, and then reinstate it later. + */ +int test_set_oom_score_adj(int new_val) +{ + struct sighand_struct *sighand = current->sighand; + int old_val; + + spin_lock_irq(&sighand->siglock); + old_val = current->signal->oom_score_adj; + if (new_val != old_val) { + if (new_val == OOM_SCORE_ADJ_MIN) + atomic_inc(¤t->mm->oom_disable_count); + else if (old_val == OOM_SCORE_ADJ_MIN) + atomic_dec(¤t->mm->oom_disable_count); + current->signal->oom_score_adj = new_val; + } + spin_unlock_irq(&sighand->siglock); + + return old_val; +} + #ifdef CONFIG_NUMA /** * has_intersects_mems_allowed() - check task eligiblity for kill @@ -154,15 +181,6 @@ unsigned int oom_badness(struct task_struct *p, struct mem_cgroup *mem, return 0; } - /* - * When the PF_OOM_ORIGIN bit is set, it indicates the task should have - * priority for oom killing. - */ - if (p->flags & PF_OOM_ORIGIN) { - task_unlock(p); - return 1000; - } - /* * The memory controller may have a limit of 0 bytes, so avoid a divide * by zero, if necessary. diff --git a/mm/swapfile.c b/mm/swapfile.c index 8c6b3ce38f09..d537d29e9b7b 100644 --- a/mm/swapfile.c +++ b/mm/swapfile.c @@ -31,6 +31,7 @@ #include #include #include +#include #include #include @@ -1555,6 +1556,7 @@ SYSCALL_DEFINE1(swapoff, const char __user *, specialfile) struct address_space *mapping; struct inode *inode; char *pathname; + int oom_score_adj; int i, type, prev; int err; @@ -1613,9 +1615,9 @@ SYSCALL_DEFINE1(swapoff, const char __user *, specialfile) p->flags &= ~SWP_WRITEOK; spin_unlock(&swap_lock); - current->flags |= PF_OOM_ORIGIN; + oom_score_adj = test_set_oom_score_adj(OOM_SCORE_ADJ_MAX); err = try_to_unuse(type); - current->flags &= ~PF_OOM_ORIGIN; + test_set_oom_score_adj(oom_score_adj); if (err) { /*