tile/mm/fault.c: Port OOM changes to handle_page_fault
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 tile.
Signed-off-by: Kautuk Consul <consul.kautuk@gmail.com>
[cmetcalf@tilera.com: initialize "flags" after "write" updated.]
Signed-off-by: Chris Metcalf <cmetcalf@tilera.com>
diff --git a/arch/tile/mm/fault.c b/arch/tile/mm/fault.c
index 54f18fc2..84ce7ab 100644
--- a/arch/tile/mm/fault.c
+++ b/arch/tile/mm/fault.c
@@ -273,11 +273,15 @@
int si_code;
int is_kernel_mode;
pgd_t *pgd;
+ unsigned int flags;
/* on TILE, protection faults are always writes */
if (!is_page_fault)
write = 1;
+ flags = (FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE |
+ (write ? FAULT_FLAG_WRITE : 0));
+
is_kernel_mode = (EX1_PL(regs->ex1) != USER_PL);
tsk = validate_current();
@@ -382,6 +386,8 @@
vma = NULL; /* happy compiler */
goto bad_area_nosemaphore;
}
+
+retry:
down_read(&mm->mmap_sem);
}
@@ -429,7 +435,11 @@
* make sure we exit gracefully rather than endlessly redo
* the fault.
*/
- fault = handle_mm_fault(mm, vma, address, write);
+ fault = handle_mm_fault(mm, vma, address, flags);
+
+ if ((fault & VM_FAULT_RETRY) && fatal_signal_pending(current))
+ return 0;
+
if (unlikely(fault & VM_FAULT_ERROR)) {
if (fault & VM_FAULT_OOM)
goto out_of_memory;
@@ -437,10 +447,22 @@
goto do_sigbus;
BUG();
}
- if (fault & VM_FAULT_MAJOR)
- tsk->maj_flt++;
- else
- tsk->min_flt++;
+ if (flags & FAULT_FLAG_ALLOW_RETRY) {
+ if (fault & VM_FAULT_MAJOR)
+ tsk->maj_flt++;
+ else
+ tsk->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;
+ }
+ }
#if CHIP_HAS_TILE_DMA() || CHIP_HAS_SN_PROC()
/*