lkml.org 
[lkml]   [2012]   [Mar]   [20]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
From
Subject[PATCH 15/20] unicore32/mm/fault.c: Port OOM changes to do_pf
Date
Commit d065bd810b6deb67d4897a14bfe21f8eb526ba99
(mm: retry page fault when blocking on disk transfer) and
commit 37b23e0525d393d48a7d59f870b3bc061a30ccdb
(x86,mm: make pagefault killable)

The above commits introduced changes into the x86 pagefault handler
for making the page fault handler retryable as well as killable.

These changes reduce the mmap_sem hold time, which is crucial
during OOM killer invocation.

Port these changes to unicore32.

Signed-off-by: Kautuk Consul <consul.kautuk@gmail.com>
---
arch/unicore32/mm/fault.c | 37 +++++++++++++++++++++++++++----------
1 files changed, 27 insertions(+), 10 deletions(-)

diff --git a/arch/unicore32/mm/fault.c b/arch/unicore32/mm/fault.c
index 283aa4b..db40765 100644
--- a/arch/unicore32/mm/fault.c
+++ b/arch/unicore32/mm/fault.c
@@ -169,7 +169,7 @@ static inline bool access_error(unsigned int fsr, struct vm_area_struct *vma)
}

static int __do_pf(struct mm_struct *mm, unsigned long addr, unsigned int fsr,
- struct task_struct *tsk)
+ unsigned int flags, struct task_struct *tsk)
{
struct vm_area_struct *vma;
int fault;
@@ -195,14 +195,7 @@ good_area:
* If for any reason at all we couldn't handle the fault, make
* sure we exit gracefully rather than endlessly redo the fault.
*/
- fault = handle_mm_fault(mm, vma, addr & PAGE_MASK,
- (!(fsr ^ 0x12)) ? FAULT_FLAG_WRITE : 0);
- if (unlikely(fault & VM_FAULT_ERROR))
- return fault;
- if (fault & VM_FAULT_MAJOR)
- tsk->maj_flt++;
- else
- tsk->min_flt++;
+ fault = handle_mm_fault(mm, vma, addr & PAGE_MASK, flags);
return fault;

check_stack:
@@ -217,6 +210,8 @@ static int do_pf(unsigned long addr, unsigned int fsr, struct pt_regs *regs)
struct task_struct *tsk;
struct mm_struct *mm;
int fault, sig, code;
+ unsigned int flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE |
+ ((!(fsr ^ 0x12)) ? FAULT_FLAG_WRITE : 0);

tsk = current;
mm = tsk->mm;
@@ -237,6 +232,7 @@ static int do_pf(unsigned long addr, unsigned int fsr, struct pt_regs *regs)
if (!user_mode(regs)
&& !search_exception_tables(regs->UCreg_pc))
goto no_context;
+retry:
down_read(&mm->mmap_sem);
} else {
/*
@@ -252,7 +248,28 @@ static int do_pf(unsigned long addr, unsigned int fsr, struct pt_regs *regs)
#endif
}

- fault = __do_pf(mm, addr, fsr, tsk);
+ fault = __do_pf(mm, addr, fsr, flags, tsk);
+
+ /* If we need to retry but a fatal signal is pending, handle the
+ * signal first. We do not need to release the mmap_sem because
+ * it would already be released in __lock_page_or_retry in
+ * mm/filemap.c. */
+ if ((fault & VM_FAULT_RETRY) && fatal_signal_pending(current))
+ return 0;
+
+ if (!(fault & VM_FAULT_ERROR) && (flags & FAULT_FLAG_ALLOW_RETRY)) {
+ if (fault & VM_FAULT_MAJOR)
+ tsk->maj_flt++;
+ else
+ tsk->min_flt++;
+ if (fault & VM_FAULT_RETRY) {
+ /* Clear FAULT_FLAG_ALLOW_RETRY to avoid any risk
+ * of starvation. */
+ flags &= ~FAULT_FLAG_ALLOW_RETRY;
+ goto retry;
+ }
+ }
+
up_read(&mm->mmap_sem);

/*
--
1.7.5.4


\
 
 \ /
  Last update: 2012-03-20 14:27    [W:0.048 / U:9.636 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site