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Commit 140ffcec4def3ee3af7565b2cf1d3b2580f7e180

Authored by Andrew Morton
Committed by Linus Torvalds
1 parent b1e2d907cb
Exists in master and in 7 other branches imx_3.0.35_4.1.0, imx_3.10.17_1.0.1_ga, imx_3.10.53_1.1.0_ga, imx_3.14.28_1.0.0_ga, smarc-imx_3.10.53_1.1.0_ga, smarc-imx_3.14.28_1.0.0_ga, smarc-l5.0.0_1.0.0-ga

[PATCH] out_of_memory() locking fix 

I seem to have lost this read_unlock().

While we're there, let's turn that interruptible sleep unto uninterruptible,
so we don't get a busywait if signal_pending().  (Again.  We seem to have a
habit of doing this).

Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

Showing 1 changed file with 2 additions and 1 deletions Inline Diff

1 /* 1 /*
2 * linux/mm/oom_kill.c 2 * linux/mm/oom_kill.c
3 * 3 *
4 * Copyright (C) 1998,2000 Rik van Riel 4 * Copyright (C) 1998,2000 Rik van Riel
5 * Thanks go out to Claus Fischer for some serious inspiration and 5 * Thanks go out to Claus Fischer for some serious inspiration and
6 * for goading me into coding this file... 6 * for goading me into coding this file...
7 * 7 *
8 * The routines in this file are used to kill a process when 8 * The routines in this file are used to kill a process when
9 * we're seriously out of memory. This gets called from __alloc_pages() 9 * we're seriously out of memory. This gets called from __alloc_pages()
10 * in mm/page_alloc.c when we really run out of memory. 10 * in mm/page_alloc.c when we really run out of memory.
11 * 11 *
12 * Since we won't call these routines often (on a well-configured 12 * Since we won't call these routines often (on a well-configured
13 * machine) this file will double as a 'coding guide' and a signpost 13 * machine) this file will double as a 'coding guide' and a signpost
14 * for newbie kernel hackers. It features several pointers to major 14 * for newbie kernel hackers. It features several pointers to major
15 * kernel subsystems and hints as to where to find out what things do. 15 * kernel subsystems and hints as to where to find out what things do.
16 */ 16 */
17 17
18 #include <linux/mm.h> 18 #include <linux/mm.h>
19 #include <linux/sched.h> 19 #include <linux/sched.h>
20 #include <linux/swap.h> 20 #include <linux/swap.h>
21 #include <linux/timex.h> 21 #include <linux/timex.h>
22 #include <linux/jiffies.h> 22 #include <linux/jiffies.h>
23 #include <linux/cpuset.h> 23 #include <linux/cpuset.h>
24 24
25 /* #define DEBUG */ 25 /* #define DEBUG */
26 26
27 /** 27 /**
28 * oom_badness - calculate a numeric value for how bad this task has been 28 * oom_badness - calculate a numeric value for how bad this task has been
29 * @p: task struct of which task we should calculate 29 * @p: task struct of which task we should calculate
30 * @uptime: current uptime in seconds 30 * @uptime: current uptime in seconds
31 * 31 *
32 * The formula used is relatively simple and documented inline in the 32 * The formula used is relatively simple and documented inline in the
33 * function. The main rationale is that we want to select a good task 33 * function. The main rationale is that we want to select a good task
34 * to kill when we run out of memory. 34 * to kill when we run out of memory.
35 * 35 *
36 * Good in this context means that: 36 * Good in this context means that:
37 * 1) we lose the minimum amount of work done 37 * 1) we lose the minimum amount of work done
38 * 2) we recover a large amount of memory 38 * 2) we recover a large amount of memory
39 * 3) we don't kill anything innocent of eating tons of memory 39 * 3) we don't kill anything innocent of eating tons of memory
40 * 4) we want to kill the minimum amount of processes (one) 40 * 4) we want to kill the minimum amount of processes (one)
41 * 5) we try to kill the process the user expects us to kill, this 41 * 5) we try to kill the process the user expects us to kill, this
42 * algorithm has been meticulously tuned to meet the principle 42 * algorithm has been meticulously tuned to meet the principle
43 * of least surprise ... (be careful when you change it) 43 * of least surprise ... (be careful when you change it)
44 */ 44 */
45 45
46 unsigned long badness(struct task_struct *p, unsigned long uptime) 46 unsigned long badness(struct task_struct *p, unsigned long uptime)
47 { 47 {
48 unsigned long points, cpu_time, run_time, s; 48 unsigned long points, cpu_time, run_time, s;
49 struct list_head *tsk; 49 struct list_head *tsk;
50 50
51 if (!p->mm) 51 if (!p->mm)
52 return 0; 52 return 0;
53 53
54 /* 54 /*
55 * The memory size of the process is the basis for the badness. 55 * The memory size of the process is the basis for the badness.
56 */ 56 */
57 points = p->mm->total_vm; 57 points = p->mm->total_vm;
58 58
59 /* 59 /*
60 * Processes which fork a lot of child processes are likely 60 * Processes which fork a lot of child processes are likely
61 * a good choice. We add half the vmsize of the children if they 61 * a good choice. We add half the vmsize of the children if they
62 * have an own mm. This prevents forking servers to flood the 62 * have an own mm. This prevents forking servers to flood the
63 * machine with an endless amount of children. In case a single 63 * machine with an endless amount of children. In case a single
64 * child is eating the vast majority of memory, adding only half 64 * child is eating the vast majority of memory, adding only half
65 * to the parents will make the child our kill candidate of choice. 65 * to the parents will make the child our kill candidate of choice.
66 */ 66 */
67 list_for_each(tsk, &p->children) { 67 list_for_each(tsk, &p->children) {
68 struct task_struct *chld; 68 struct task_struct *chld;
69 chld = list_entry(tsk, struct task_struct, sibling); 69 chld = list_entry(tsk, struct task_struct, sibling);
70 if (chld->mm != p->mm && chld->mm) 70 if (chld->mm != p->mm && chld->mm)
71 points += chld->mm->total_vm/2 + 1; 71 points += chld->mm->total_vm/2 + 1;
72 } 72 }
73 73
74 /* 74 /*
75 * CPU time is in tens of seconds and run time is in thousands 75 * CPU time is in tens of seconds and run time is in thousands
76 * of seconds. There is no particular reason for this other than 76 * of seconds. There is no particular reason for this other than
77 * that it turned out to work very well in practice. 77 * that it turned out to work very well in practice.
78 */ 78 */
79 cpu_time = (cputime_to_jiffies(p->utime) + cputime_to_jiffies(p->stime)) 79 cpu_time = (cputime_to_jiffies(p->utime) + cputime_to_jiffies(p->stime))
80 >> (SHIFT_HZ + 3); 80 >> (SHIFT_HZ + 3);
81 81
82 if (uptime >= p->start_time.tv_sec) 82 if (uptime >= p->start_time.tv_sec)
83 run_time = (uptime - p->start_time.tv_sec) >> 10; 83 run_time = (uptime - p->start_time.tv_sec) >> 10;
84 else 84 else
85 run_time = 0; 85 run_time = 0;
86 86
87 s = int_sqrt(cpu_time); 87 s = int_sqrt(cpu_time);
88 if (s) 88 if (s)
89 points /= s; 89 points /= s;
90 s = int_sqrt(int_sqrt(run_time)); 90 s = int_sqrt(int_sqrt(run_time));
91 if (s) 91 if (s)
92 points /= s; 92 points /= s;
93 93
94 /* 94 /*
95 * Niced processes are most likely less important, so double 95 * Niced processes are most likely less important, so double
96 * their badness points. 96 * their badness points.
97 */ 97 */
98 if (task_nice(p) > 0) 98 if (task_nice(p) > 0)
99 points *= 2; 99 points *= 2;
100 100
101 /* 101 /*
102 * Superuser processes are usually more important, so we make it 102 * Superuser processes are usually more important, so we make it
103 * less likely that we kill those. 103 * less likely that we kill those.
104 */ 104 */
105 if (cap_t(p->cap_effective) & CAP_TO_MASK(CAP_SYS_ADMIN) || 105 if (cap_t(p->cap_effective) & CAP_TO_MASK(CAP_SYS_ADMIN) ||
106 p->uid == 0 || p->euid == 0) 106 p->uid == 0 || p->euid == 0)
107 points /= 4; 107 points /= 4;
108 108
109 /* 109 /*
110 * We don't want to kill a process with direct hardware access. 110 * We don't want to kill a process with direct hardware access.
111 * Not only could that mess up the hardware, but usually users 111 * Not only could that mess up the hardware, but usually users
112 * tend to only have this flag set on applications they think 112 * tend to only have this flag set on applications they think
113 * of as important. 113 * of as important.
114 */ 114 */
115 if (cap_t(p->cap_effective) & CAP_TO_MASK(CAP_SYS_RAWIO)) 115 if (cap_t(p->cap_effective) & CAP_TO_MASK(CAP_SYS_RAWIO))
116 points /= 4; 116 points /= 4;
117 117
118 /* 118 /*
119 * Adjust the score by oomkilladj. 119 * Adjust the score by oomkilladj.
120 */ 120 */
121 if (p->oomkilladj) { 121 if (p->oomkilladj) {
122 if (p->oomkilladj > 0) 122 if (p->oomkilladj > 0)
123 points <<= p->oomkilladj; 123 points <<= p->oomkilladj;
124 else 124 else
125 points >>= -(p->oomkilladj); 125 points >>= -(p->oomkilladj);
126 } 126 }
127 127
128 #ifdef DEBUG 128 #ifdef DEBUG
129 printk(KERN_DEBUG "OOMkill: task %d (%s) got %d points\n", 129 printk(KERN_DEBUG "OOMkill: task %d (%s) got %d points\n",
130 p->pid, p->comm, points); 130 p->pid, p->comm, points);
131 #endif 131 #endif
132 return points; 132 return points;
133 } 133 }
134 134
135 /* 135 /*
136 * Types of limitations to the nodes from which allocations may occur 136 * Types of limitations to the nodes from which allocations may occur
137 */ 137 */
138 #define CONSTRAINT_NONE 1 138 #define CONSTRAINT_NONE 1
139 #define CONSTRAINT_MEMORY_POLICY 2 139 #define CONSTRAINT_MEMORY_POLICY 2
140 #define CONSTRAINT_CPUSET 3 140 #define CONSTRAINT_CPUSET 3
141 141
142 /* 142 /*
143 * Determine the type of allocation constraint. 143 * Determine the type of allocation constraint.
144 */ 144 */
145 static inline int constrained_alloc(struct zonelist *zonelist, gfp_t gfp_mask) 145 static inline int constrained_alloc(struct zonelist *zonelist, gfp_t gfp_mask)
146 { 146 {
147 #ifdef CONFIG_NUMA 147 #ifdef CONFIG_NUMA
148 struct zone **z; 148 struct zone **z;
149 nodemask_t nodes = node_online_map; 149 nodemask_t nodes = node_online_map;
150 150
151 for (z = zonelist->zones; *z; z++) 151 for (z = zonelist->zones; *z; z++)
152 if (cpuset_zone_allowed(*z, gfp_mask)) 152 if (cpuset_zone_allowed(*z, gfp_mask))
153 node_clear((*z)->zone_pgdat->node_id, 153 node_clear((*z)->zone_pgdat->node_id,
154 nodes); 154 nodes);
155 else 155 else
156 return CONSTRAINT_CPUSET; 156 return CONSTRAINT_CPUSET;
157 157
158 if (!nodes_empty(nodes)) 158 if (!nodes_empty(nodes))
159 return CONSTRAINT_MEMORY_POLICY; 159 return CONSTRAINT_MEMORY_POLICY;
160 #endif 160 #endif
161 161
162 return CONSTRAINT_NONE; 162 return CONSTRAINT_NONE;
163 } 163 }
164 164
165 /* 165 /*
166 * Simple selection loop. We chose the process with the highest 166 * Simple selection loop. We chose the process with the highest
167 * number of 'points'. We expect the caller will lock the tasklist. 167 * number of 'points'. We expect the caller will lock the tasklist.
168 * 168 *
169 * (not docbooked, we don't want this one cluttering up the manual) 169 * (not docbooked, we don't want this one cluttering up the manual)
170 */ 170 */
171 static struct task_struct *select_bad_process(unsigned long *ppoints) 171 static struct task_struct *select_bad_process(unsigned long *ppoints)
172 { 172 {
173 struct task_struct *g, *p; 173 struct task_struct *g, *p;
174 struct task_struct *chosen = NULL; 174 struct task_struct *chosen = NULL;
175 struct timespec uptime; 175 struct timespec uptime;
176 *ppoints = 0; 176 *ppoints = 0;
177 177
178 do_posix_clock_monotonic_gettime(&uptime); 178 do_posix_clock_monotonic_gettime(&uptime);
179 do_each_thread(g, p) { 179 do_each_thread(g, p) {
180 unsigned long points; 180 unsigned long points;
181 int releasing; 181 int releasing;
182 182
183 /* skip the init task with pid == 1 */ 183 /* skip the init task with pid == 1 */
184 if (p->pid == 1) 184 if (p->pid == 1)
185 continue; 185 continue;
186 if (p->oomkilladj == OOM_DISABLE) 186 if (p->oomkilladj == OOM_DISABLE)
187 continue; 187 continue;
188 /* If p's nodes don't overlap ours, it won't help to kill p. */ 188 /* If p's nodes don't overlap ours, it won't help to kill p. */
189 if (!cpuset_excl_nodes_overlap(p)) 189 if (!cpuset_excl_nodes_overlap(p))
190 continue; 190 continue;
191 191
192 /* 192 /*
193 * This is in the process of releasing memory so for wait it 193 * This is in the process of releasing memory so for wait it
194 * to finish before killing some other task by mistake. 194 * to finish before killing some other task by mistake.
195 */ 195 */
196 releasing = test_tsk_thread_flag(p, TIF_MEMDIE) || 196 releasing = test_tsk_thread_flag(p, TIF_MEMDIE) ||
197 p->flags & PF_EXITING; 197 p->flags & PF_EXITING;
198 if (releasing && !(p->flags & PF_DEAD)) 198 if (releasing && !(p->flags & PF_DEAD))
199 return ERR_PTR(-1UL); 199 return ERR_PTR(-1UL);
200 if (p->flags & PF_SWAPOFF) 200 if (p->flags & PF_SWAPOFF)
201 return p; 201 return p;
202 202
203 points = badness(p, uptime.tv_sec); 203 points = badness(p, uptime.tv_sec);
204 if (points > *ppoints || !chosen) { 204 if (points > *ppoints || !chosen) {
205 chosen = p; 205 chosen = p;
206 *ppoints = points; 206 *ppoints = points;
207 } 207 }
208 } while_each_thread(g, p); 208 } while_each_thread(g, p);
209 return chosen; 209 return chosen;
210 } 210 }
211 211
212 /** 212 /**
213 * We must be careful though to never send SIGKILL a process with 213 * We must be careful though to never send SIGKILL a process with
214 * CAP_SYS_RAW_IO set, send SIGTERM instead (but it's unlikely that 214 * CAP_SYS_RAW_IO set, send SIGTERM instead (but it's unlikely that
215 * we select a process with CAP_SYS_RAW_IO set). 215 * we select a process with CAP_SYS_RAW_IO set).
216 */ 216 */
217 static void __oom_kill_task(task_t *p, const char *message) 217 static void __oom_kill_task(task_t *p, const char *message)
218 { 218 {
219 if (p->pid == 1) { 219 if (p->pid == 1) {
220 WARN_ON(1); 220 WARN_ON(1);
221 printk(KERN_WARNING "tried to kill init!\n"); 221 printk(KERN_WARNING "tried to kill init!\n");
222 return; 222 return;
223 } 223 }
224 224
225 task_lock(p); 225 task_lock(p);
226 if (!p->mm || p->mm == &init_mm) { 226 if (!p->mm || p->mm == &init_mm) {
227 WARN_ON(1); 227 WARN_ON(1);
228 printk(KERN_WARNING "tried to kill an mm-less task!\n"); 228 printk(KERN_WARNING "tried to kill an mm-less task!\n");
229 task_unlock(p); 229 task_unlock(p);
230 return; 230 return;
231 } 231 }
232 task_unlock(p); 232 task_unlock(p);
233 printk(KERN_ERR "%s: Killed process %d (%s).\n", 233 printk(KERN_ERR "%s: Killed process %d (%s).\n",
234 message, p->pid, p->comm); 234 message, p->pid, p->comm);
235 235
236 /* 236 /*
237 * We give our sacrificial lamb high priority and access to 237 * We give our sacrificial lamb high priority and access to
238 * all the memory it needs. That way it should be able to 238 * all the memory it needs. That way it should be able to
239 * exit() and clear out its resources quickly... 239 * exit() and clear out its resources quickly...
240 */ 240 */
241 p->time_slice = HZ; 241 p->time_slice = HZ;
242 set_tsk_thread_flag(p, TIF_MEMDIE); 242 set_tsk_thread_flag(p, TIF_MEMDIE);
243 243
244 force_sig(SIGKILL, p); 244 force_sig(SIGKILL, p);
245 } 245 }
246 246
247 static struct mm_struct *oom_kill_task(task_t *p, const char *message) 247 static struct mm_struct *oom_kill_task(task_t *p, const char *message)
248 { 248 {
249 struct mm_struct *mm = get_task_mm(p); 249 struct mm_struct *mm = get_task_mm(p);
250 task_t * g, * q; 250 task_t * g, * q;
251 251
252 if (!mm) 252 if (!mm)
253 return NULL; 253 return NULL;
254 if (mm == &init_mm) { 254 if (mm == &init_mm) {
255 mmput(mm); 255 mmput(mm);
256 return NULL; 256 return NULL;
257 } 257 }
258 258
259 __oom_kill_task(p, message); 259 __oom_kill_task(p, message);
260 /* 260 /*
261 * kill all processes that share the ->mm (i.e. all threads), 261 * kill all processes that share the ->mm (i.e. all threads),
262 * but are in a different thread group 262 * but are in a different thread group
263 */ 263 */
264 do_each_thread(g, q) 264 do_each_thread(g, q)
265 if (q->mm == mm && q->tgid != p->tgid) 265 if (q->mm == mm && q->tgid != p->tgid)
266 __oom_kill_task(q, message); 266 __oom_kill_task(q, message);
267 while_each_thread(g, q); 267 while_each_thread(g, q);
268 268
269 return mm; 269 return mm;
270 } 270 }
271 271
272 static struct mm_struct *oom_kill_process(struct task_struct *p, 272 static struct mm_struct *oom_kill_process(struct task_struct *p,
273 unsigned long points, const char *message) 273 unsigned long points, const char *message)
274 { 274 {
275 struct mm_struct *mm; 275 struct mm_struct *mm;
276 struct task_struct *c; 276 struct task_struct *c;
277 struct list_head *tsk; 277 struct list_head *tsk;
278 278
279 printk(KERN_ERR "Out of Memory: Kill process %d (%s) score %li and " 279 printk(KERN_ERR "Out of Memory: Kill process %d (%s) score %li and "
280 "children.\n", p->pid, p->comm, points); 280 "children.\n", p->pid, p->comm, points);
281 /* Try to kill a child first */ 281 /* Try to kill a child first */
282 list_for_each(tsk, &p->children) { 282 list_for_each(tsk, &p->children) {
283 c = list_entry(tsk, struct task_struct, sibling); 283 c = list_entry(tsk, struct task_struct, sibling);
284 if (c->mm == p->mm) 284 if (c->mm == p->mm)
285 continue; 285 continue;
286 mm = oom_kill_task(c, message); 286 mm = oom_kill_task(c, message);
287 if (mm) 287 if (mm)
288 return mm; 288 return mm;
289 } 289 }
290 return oom_kill_task(p, message); 290 return oom_kill_task(p, message);
291 } 291 }
292 292
293 /** 293 /**
294 * oom_kill - kill the "best" process when we run out of memory 294 * oom_kill - kill the "best" process when we run out of memory
295 * 295 *
296 * If we run out of memory, we have the choice between either 296 * If we run out of memory, we have the choice between either
297 * killing a random task (bad), letting the system crash (worse) 297 * killing a random task (bad), letting the system crash (worse)
298 * OR try to be smart about which process to kill. Note that we 298 * OR try to be smart about which process to kill. Note that we
299 * don't have to be perfect here, we just have to be good. 299 * don't have to be perfect here, we just have to be good.
300 */ 300 */
301 void out_of_memory(struct zonelist *zonelist, gfp_t gfp_mask, int order) 301 void out_of_memory(struct zonelist *zonelist, gfp_t gfp_mask, int order)
302 { 302 {
303 struct mm_struct *mm = NULL; 303 struct mm_struct *mm = NULL;
304 task_t *p; 304 task_t *p;
305 unsigned long points = 0; 305 unsigned long points = 0;
306 306
307 if (printk_ratelimit()) { 307 if (printk_ratelimit()) {
308 printk("oom-killer: gfp_mask=0x%x, order=%d\n", 308 printk("oom-killer: gfp_mask=0x%x, order=%d\n",
309 gfp_mask, order); 309 gfp_mask, order);
310 dump_stack(); 310 dump_stack();
311 show_mem(); 311 show_mem();
312 } 312 }
313 313
314 cpuset_lock(); 314 cpuset_lock();
315 read_lock(&tasklist_lock); 315 read_lock(&tasklist_lock);
316 316
317 /* 317 /*
318 * Check if there were limitations on the allocation (only relevant for 318 * Check if there were limitations on the allocation (only relevant for
319 * NUMA) that may require different handling. 319 * NUMA) that may require different handling.
320 */ 320 */
321 switch (constrained_alloc(zonelist, gfp_mask)) { 321 switch (constrained_alloc(zonelist, gfp_mask)) {
322 case CONSTRAINT_MEMORY_POLICY: 322 case CONSTRAINT_MEMORY_POLICY:
323 mm = oom_kill_process(current, points, 323 mm = oom_kill_process(current, points,
324 "No available memory (MPOL_BIND)"); 324 "No available memory (MPOL_BIND)");
325 break; 325 break;
326 326
327 case CONSTRAINT_CPUSET: 327 case CONSTRAINT_CPUSET:
328 mm = oom_kill_process(current, points, 328 mm = oom_kill_process(current, points,
329 "No available memory in cpuset"); 329 "No available memory in cpuset");
330 break; 330 break;
331 331
332 case CONSTRAINT_NONE: 332 case CONSTRAINT_NONE:
333 retry: 333 retry:
334 /* 334 /*
335 * Rambo mode: Shoot down a process and hope it solves whatever 335 * Rambo mode: Shoot down a process and hope it solves whatever
336 * issues we may have. 336 * issues we may have.
337 */ 337 */
338 p = select_bad_process(&points); 338 p = select_bad_process(&points);
339 339
340 if (PTR_ERR(p) == -1UL) 340 if (PTR_ERR(p) == -1UL)
341 goto out; 341 goto out;
342 342
343 /* Found nothing?!?! Either we hang forever, or we panic. */ 343 /* Found nothing?!?! Either we hang forever, or we panic. */
344 if (!p) { 344 if (!p) {
345 read_unlock(&tasklist_lock); 345 read_unlock(&tasklist_lock);
346 cpuset_unlock(); 346 cpuset_unlock();
347 panic("Out of memory and no killable processes...\n"); 347 panic("Out of memory and no killable processes...\n");
348 } 348 }
349 349
350 mm = oom_kill_process(p, points, "Out of memory"); 350 mm = oom_kill_process(p, points, "Out of memory");
351 if (!mm) 351 if (!mm)
352 goto retry; 352 goto retry;
353 353
354 break; 354 break;
355 } 355 }
356 356
357 out: 357 out:
358 read_unlock(&tasklist_lock);
358 cpuset_unlock(); 359 cpuset_unlock();
359 if (mm) 360 if (mm)
360 mmput(mm); 361 mmput(mm);
361 362
362 /* 363 /*
363 * Give "p" a good chance of killing itself before we 364 * Give "p" a good chance of killing itself before we
364 * retry to allocate memory unless "p" is current 365 * retry to allocate memory unless "p" is current
365 */ 366 */
366 if (!test_thread_flag(TIF_MEMDIE)) 367 if (!test_thread_flag(TIF_MEMDIE))
367 schedule_timeout_interruptible(1); 368 schedule_timeout_uninterruptible(1);
368 } 369 }
369 370