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 14/20] xtensa/mm/fault.c: Port OOM changes to do_page_fault
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 xtensa.

Signed-off-by: Kautuk Consul <consul.kautuk@gmail.com>
---
arch/xtensa/mm/fault.c | 30 +++++++++++++++++++++++++-----
1 files changed, 25 insertions(+), 5 deletions(-)

diff --git a/arch/xtensa/mm/fault.c b/arch/xtensa/mm/fault.c
index e367e30..f570bfd 100644
--- a/arch/xtensa/mm/fault.c
+++ b/arch/xtensa/mm/fault.c
@@ -45,6 +45,7 @@ void do_page_fault(struct pt_regs *regs)

int is_write, is_exec;
int fault;
+ unsigned int flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE;

info.si_code = SEGV_MAPERR;

@@ -72,6 +73,7 @@ void do_page_fault(struct pt_regs *regs)
address, exccause, regs->pc, is_write? "w":"", is_exec? "x":"");
#endif

+retry:
down_read(&mm->mmap_sem);
vma = find_vma(mm, address);

@@ -94,6 +96,7 @@ good_area:
if (is_write) {
if (!(vma->vm_flags & VM_WRITE))
goto bad_area;
+ flags |= FAULT_FLAG_WRITE;
} else if (is_exec) {
if (!(vma->vm_flags & VM_EXEC))
goto bad_area;
@@ -105,7 +108,11 @@ good_area:
* make sure we exit gracefully rather than endlessly redo
* the fault.
*/
- fault = handle_mm_fault(mm, vma, address, is_write ? FAULT_FLAG_WRITE : 0);
+ fault = handle_mm_fault(mm, vma, address, flags);
+
+ if ((fault & VM_FAULT_RETRY) && fatal_signal_pending(current))
+ return;
+
if (unlikely(fault & VM_FAULT_ERROR)) {
if (fault & VM_FAULT_OOM)
goto out_of_memory;
@@ -113,10 +120,23 @@ good_area:
goto do_sigbus;
BUG();
}
- if (fault & VM_FAULT_MAJOR)
- current->maj_flt++;
- else
- current->min_flt++;
+ if (flags & FAULT_FLAG_ALLOW_RETRY) {
+ if (fault & VM_FAULT_MAJOR)
+ current->maj_flt++;
+ else
+ current->min_flt++;
+ if (fault & VM_FAULT_RETRY) {
+ flags &= ~FAULT_FLAG_ALLOW_RETRY;
+
+ /*
+ * No need to up_read(&mm->mmap_sem) as we would
+ * have already released it in __lock_page_or_retry
+ * in mm/filemap.c.
+ */
+
+ goto retry;
+ }
+ }

up_read(&mm->mmap_sem);
return;
--
1.7.5.4


\
 
 \ /
  Last update: 2012-03-20 14:27    [W:0.027 / U:4.236 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site