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authorKOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>2011-05-24 17:11:30 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2011-05-25 08:39:08 -0700
commit37b23e0525d393d48a7d59f870b3bc061a30ccdb (patch)
tree467e6fcd785108a21d836e1aad8fc1a68aa72e17
parentf62e00cc3a00bfbd394a79fc22b334c31f91bd5f (diff)
downloadop-kernel-dev-37b23e0525d393d48a7d59f870b3bc061a30ccdb.zip
op-kernel-dev-37b23e0525d393d48a7d59f870b3bc061a30ccdb.tar.gz
x86,mm: make pagefault killable
When an oom killing occurs, almost all processes are getting stuck at the following two points. 1) __alloc_pages_nodemask 2) __lock_page_or_retry 1) is not very problematic because TIF_MEMDIE leads to an allocation failure and getting out from page allocator. 2) is more problematic. In an OOM situation, zones typically don't have page cache at all and memory starvation might lead to greatly reduced IO performance. When a fork bomb occurs, TIF_MEMDIE tasks don't die quickly, meaning that a fork bomb may create new process quickly rather than the oom-killer killing it. Then, the system may become livelocked. This patch makes the pagefault interruptible by SIGKILL. Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Reviewed-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Minchan Kim <minchan.kim@gmail.com> Cc: Matthew Wilcox <willy@linux.intel.com> Cc: Ingo Molnar <mingo@elte.hu> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: "H. Peter Anvin" <hpa@zytor.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
-rw-r--r--arch/x86/mm/fault.c12
-rw-r--r--include/linux/mm.h1
-rw-r--r--mm/filemap.c31
3 files changed, 36 insertions, 8 deletions
diff --git a/arch/x86/mm/fault.c b/arch/x86/mm/fault.c
index bcb394d..f7a2a05 100644
--- a/arch/x86/mm/fault.c
+++ b/arch/x86/mm/fault.c
@@ -965,7 +965,7 @@ do_page_fault(struct pt_regs *regs, unsigned long error_code)
struct mm_struct *mm;
int fault;
int write = error_code & PF_WRITE;
- unsigned int flags = FAULT_FLAG_ALLOW_RETRY |
+ unsigned int flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE |
(write ? FAULT_FLAG_WRITE : 0);
tsk = current;
@@ -1139,6 +1139,16 @@ good_area:
}
/*
+ * Pagefault was interrupted by SIGKILL. We have no reason to
+ * continue pagefault.
+ */
+ if ((fault & VM_FAULT_RETRY) && fatal_signal_pending(current)) {
+ if (!(error_code & PF_USER))
+ no_context(regs, error_code, address);
+ return;
+ }
+
+ /*
* Major/minor page fault accounting is only done on the
* initial attempt. If we go through a retry, it is extremely
* likely that the page will be found in page cache at that point.
diff --git a/include/linux/mm.h b/include/linux/mm.h
index 1746f67..57d3d5f 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -153,6 +153,7 @@ extern pgprot_t protection_map[16];
#define FAULT_FLAG_MKWRITE 0x04 /* Fault was mkwrite of existing pte */
#define FAULT_FLAG_ALLOW_RETRY 0x08 /* Retry fault if blocking */
#define FAULT_FLAG_RETRY_NOWAIT 0x10 /* Don't drop mmap_sem and wait when retrying */
+#define FAULT_FLAG_KILLABLE 0x20 /* The fault task is in SIGKILL killable region */
/*
* This interface is used by x86 PAT code to identify a pfn mapping that is
diff --git a/mm/filemap.c b/mm/filemap.c
index dea8a38..8144f87 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -654,15 +654,32 @@ EXPORT_SYMBOL_GPL(__lock_page_killable);
int __lock_page_or_retry(struct page *page, struct mm_struct *mm,
unsigned int flags)
{
- if (!(flags & FAULT_FLAG_ALLOW_RETRY)) {
- __lock_page(page);
- return 1;
- } else {
- if (!(flags & FAULT_FLAG_RETRY_NOWAIT)) {
- up_read(&mm->mmap_sem);
+ if (flags & FAULT_FLAG_ALLOW_RETRY) {
+ /*
+ * CAUTION! In this case, mmap_sem is not released
+ * even though return 0.
+ */
+ if (flags & FAULT_FLAG_RETRY_NOWAIT)
+ return 0;
+
+ up_read(&mm->mmap_sem);
+ if (flags & FAULT_FLAG_KILLABLE)
+ wait_on_page_locked_killable(page);
+ else
wait_on_page_locked(page);
- }
return 0;
+ } else {
+ if (flags & FAULT_FLAG_KILLABLE) {
+ int ret;
+
+ ret = __lock_page_killable(page);
+ if (ret) {
+ up_read(&mm->mmap_sem);
+ return 0;
+ }
+ } else
+ __lock_page(page);
+ return 1;
}
}
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