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git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
nios2: Port OOM changes to do_page_fault()
Commit d065bd810b6d ("mm: retry page fault when blocking on disk transfer") and
and commit 37b23e0525d3 ("x86,mm: make pagefault killable")
The above commits introduced changes into the nios2 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.
Signed-off-by: Ley Foon Tan <lftan@altera.com>
+32
-5
+32
-5
arch/nios2/mm/fault.c
+32
-5
arch/nios2/mm/fault.c
···
47
47
struct mm_struct *mm = tsk->mm;
48
48
int code = SEGV_MAPERR;
49
49
int fault;
50
-
unsigned int flags = 0;
50
+
unsigned int flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE;
51
51
52
52
cause >>= 2;
53
53
···
86
86
if (!down_read_trylock(&mm->mmap_sem)) {
87
87
if (!user_mode(regs) && !search_exception_tables(regs->ea))
88
88
goto bad_area_nosemaphore;
89
+
retry:
89
90
down_read(&mm->mmap_sem);
90
91
}
91
92
···
133
132
* the fault.
134
133
*/
135
134
fault = handle_mm_fault(mm, vma, address, flags);
135
+
136
+
if ((fault & VM_FAULT_RETRY) && fatal_signal_pending(current))
137
+
return;
138
+
136
139
if (unlikely(fault & VM_FAULT_ERROR)) {
137
140
if (fault & VM_FAULT_OOM)
138
141
goto out_of_memory;
···
146
141
goto do_sigbus;
147
142
BUG();
148
143
}
149
-
if (fault & VM_FAULT_MAJOR)
150
-
tsk->maj_flt++;
151
-
else
152
-
tsk->min_flt++;
144
+
145
+
/*
146
+
* Major/minor page fault accounting is only done on the
147
+
* initial attempt. If we go through a retry, it is extremely
148
+
* likely that the page will be found in page cache at that point.
149
+
*/
150
+
if (flags & FAULT_FLAG_ALLOW_RETRY) {
151
+
if (fault & VM_FAULT_MAJOR)
152
+
current->maj_flt++;
153
+
else
154
+
current->min_flt++;
155
+
if (fault & VM_FAULT_RETRY) {
156
+
/* Clear FAULT_FLAG_ALLOW_RETRY to avoid any risk
157
+
* of starvation. */
158
+
flags &= ~FAULT_FLAG_ALLOW_RETRY;
159
+
flags |= FAULT_FLAG_TRIED;
160
+
161
+
/*
162
+
* No need to up_read(&mm->mmap_sem) as we would
163
+
* have already released it in __lock_page_or_retry
164
+
* in mm/filemap.c.
165
+
*/
166
+
167
+
goto retry;
168
+
}
169
+
}
153
170
154
171
up_read(&mm->mmap_sem);
155
172
return;