From 1c0fe6e3bda0464728c23c8d84aa47567e8b716c Mon Sep 17 00:00:00 2001 From: Nick Piggin Date: Tue, 6 Jan 2009 14:38:59 -0800 Subject: [PATCH] mm: invoke oom-killer from page fault Rather than have the pagefault handler kill a process directly if it gets a VM_FAULT_OOM, have it call into the OOM killer. With increasingly sophisticated oom behaviour (cpusets, memory cgroups, oom killing throttling, oom priority adjustment or selective disabling, panic on oom, etc), it's silly to unconditionally kill the faulting process at page fault time. Create a hook for pagefault oom path to call into instead. Only converted x86 and uml so far. [akpm@linux-foundation.org: make __out_of_memory() static] [akpm@linux-foundation.org: fix comment] Signed-off-by: Nick Piggin Cc: Jeff Dike Acked-by: Ingo Molnar Cc: Thomas Gleixner Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- arch/um/kernel/trap.c | 24 ++++------- arch/x86/mm/fault.c | 24 +++-------- include/linux/mm.h | 5 +++ mm/oom_kill.c | 94 ++++++++++++++++++++++++++++++------------- 4 files changed, 84 insertions(+), 63 deletions(-) diff --git a/arch/um/kernel/trap.c b/arch/um/kernel/trap.c index 44e49041949..7384d8accfe 100644 --- a/arch/um/kernel/trap.c +++ b/arch/um/kernel/trap.c @@ -64,11 +64,10 @@ good_area: do { int fault; -survive: + fault = handle_mm_fault(mm, vma, address, is_write); if (unlikely(fault & VM_FAULT_ERROR)) { if (fault & VM_FAULT_OOM) { - err = -ENOMEM; goto out_of_memory; } else if (fault & VM_FAULT_SIGBUS) { err = -EACCES; @@ -104,18 +103,14 @@ out: out_nosemaphore: return err; -/* - * We ran out of memory, or some other thing happened to us that made - * us unable to handle the page fault gracefully. - */ out_of_memory: - if (is_global_init(current)) { - up_read(&mm->mmap_sem); - yield(); - down_read(&mm->mmap_sem); - goto survive; - } - goto out; + /* + * We ran out of memory, call the OOM killer, and return the userspace + * (which will retry the fault, or kill us if we got oom-killed). + */ + up_read(&mm->mmap_sem); + pagefault_out_of_memory(); + return 0; } static void bad_segv(struct faultinfo fi, unsigned long ip) @@ -214,9 +209,6 @@ unsigned long segv(struct faultinfo fi, unsigned long ip, int is_user, si.si_addr = (void __user *)address; current->thread.arch.faultinfo = fi; force_sig_info(SIGBUS, &si, current); - } else if (err == -ENOMEM) { - printk(KERN_INFO "VM: killing process %s\n", current->comm); - do_exit(SIGKILL); } else { BUG_ON(err != -EFAULT); si.si_signo = SIGSEGV; diff --git a/arch/x86/mm/fault.c b/arch/x86/mm/fault.c index 57ec8c86a87..9e268b6b204 100644 --- a/arch/x86/mm/fault.c +++ b/arch/x86/mm/fault.c @@ -667,7 +667,6 @@ void __kprobes do_page_fault(struct pt_regs *regs, unsigned long error_code) if (unlikely(in_atomic() || !mm)) goto bad_area_nosemaphore; -again: /* * When running in the kernel we expect faults to occur only to * addresses in user space. All other faults represent errors in the @@ -859,25 +858,14 @@ no_context: oops_end(flags, regs, sig); #endif -/* - * We ran out of memory, or some other thing happened to us that made - * us unable to handle the page fault gracefully. - */ out_of_memory: + /* + * We ran out of memory, call the OOM killer, and return the userspace + * (which will retry the fault, or kill us if we got oom-killed). + */ up_read(&mm->mmap_sem); - if (is_global_init(tsk)) { - yield(); - /* - * Re-lookup the vma - in theory the vma tree might - * have changed: - */ - goto again; - } - - printk("VM: killing process %s\n", tsk->comm); - if (error_code & PF_USER) - do_group_exit(SIGKILL); - goto no_context; + pagefault_out_of_memory(); + return; do_sigbus: up_read(&mm->mmap_sem); diff --git a/include/linux/mm.h b/include/linux/mm.h index aaa8b843be2..4a3d28c8644 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -717,6 +717,11 @@ static inline int page_mapped(struct page *page) #define VM_FAULT_ERROR (VM_FAULT_OOM | VM_FAULT_SIGBUS) +/* + * Can be called by the pagefault handler when it gets a VM_FAULT_OOM. + */ +extern void pagefault_out_of_memory(void); + #define offset_in_page(p) ((unsigned long)(p) & ~PAGE_MASK) extern void show_free_areas(void); diff --git a/mm/oom_kill.c b/mm/oom_kill.c index 558f9afe6e4..c592965dab2 100644 --- a/mm/oom_kill.c +++ b/mm/oom_kill.c @@ -509,6 +509,69 @@ void clear_zonelist_oom(struct zonelist *zonelist, gfp_t gfp_mask) spin_unlock(&zone_scan_mutex); } +/* + * Must be called with tasklist_lock held for read. + */ +static void __out_of_memory(gfp_t gfp_mask, int order) +{ + if (sysctl_oom_kill_allocating_task) { + oom_kill_process(current, gfp_mask, order, 0, NULL, + "Out of memory (oom_kill_allocating_task)"); + + } else { + unsigned long points; + struct task_struct *p; + +retry: + /* + * Rambo mode: Shoot down a process and hope it solves whatever + * issues we may have. + */ + p = select_bad_process(&points, NULL); + + if (PTR_ERR(p) == -1UL) + return; + + /* Found nothing?!?! Either we hang forever, or we panic. */ + if (!p) { + read_unlock(&tasklist_lock); + panic("Out of memory and no killable processes...\n"); + } + + if (oom_kill_process(p, gfp_mask, order, points, NULL, + "Out of memory")) + goto retry; + } +} + +/* + * pagefault handler calls into here because it is out of memory but + * doesn't know exactly how or why. + */ +void pagefault_out_of_memory(void) +{ + unsigned long freed = 0; + + blocking_notifier_call_chain(&oom_notify_list, 0, &freed); + if (freed > 0) + /* Got some memory back in the last second. */ + return; + + if (sysctl_panic_on_oom) + panic("out of memory from page fault. panic_on_oom is selected.\n"); + + read_lock(&tasklist_lock); + __out_of_memory(0, 0); /* unknown gfp_mask and order */ + read_unlock(&tasklist_lock); + + /* + * Give "p" a good chance of killing itself before we + * retry to allocate memory. + */ + if (!test_thread_flag(TIF_MEMDIE)) + schedule_timeout_uninterruptible(1); +} + /** * out_of_memory - kill the "best" process when we run out of memory * @zonelist: zonelist pointer @@ -522,8 +585,6 @@ void clear_zonelist_oom(struct zonelist *zonelist, gfp_t gfp_mask) */ void out_of_memory(struct zonelist *zonelist, gfp_t gfp_mask, int order) { - struct task_struct *p; - unsigned long points = 0; unsigned long freed = 0; enum oom_constraint constraint; @@ -544,7 +605,7 @@ void out_of_memory(struct zonelist *zonelist, gfp_t gfp_mask, int order) switch (constraint) { case CONSTRAINT_MEMORY_POLICY: - oom_kill_process(current, gfp_mask, order, points, NULL, + oom_kill_process(current, gfp_mask, order, 0, NULL, "No available memory (MPOL_BIND)"); break; @@ -553,35 +614,10 @@ void out_of_memory(struct zonelist *zonelist, gfp_t gfp_mask, int order) panic("out of memory. panic_on_oom is selected\n"); /* Fall-through */ case CONSTRAINT_CPUSET: - if (sysctl_oom_kill_allocating_task) { - oom_kill_process(current, gfp_mask, order, points, NULL, - "Out of memory (oom_kill_allocating_task)"); - break; - } -retry: - /* - * Rambo mode: Shoot down a process and hope it solves whatever - * issues we may have. - */ - p = select_bad_process(&points, NULL); - - if (PTR_ERR(p) == -1UL) - goto out; - - /* Found nothing?!?! Either we hang forever, or we panic. */ - if (!p) { - read_unlock(&tasklist_lock); - panic("Out of memory and no killable processes...\n"); - } - - if (oom_kill_process(p, gfp_mask, order, points, NULL, - "Out of memory")) - goto retry; - + __out_of_memory(gfp_mask, order); break; } -out: read_unlock(&tasklist_lock); /* -- 2.41.1