linux-kernel - [PATCH 16/19 v2] sh/mm/fault_32.c: Port OOM changes to do_page

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [thread-next>] [day] [month] [year] [list]

Message-Id: <1333195571-5455-1-git-send-email-consul.kautuk@gmail.com>
Date:	Sat, 31 Mar 2012 08:06:11 -0400
From:	Kautuk Consul <consul.kautuk@...il.com>
To:	Paul Mundt <lethal@...ux-sh.org>, Ingo Molnar <mingo@...e.hu>,
	Peter Zijlstra <a.p.zijlstra@...llo.nl>
Cc:	linux-sh@...r.kernel.org, linux-kernel@...r.kernel.org,
	Kautuk Consul <consul.kautuk@...il.com>
Subject: [PATCH 16/19 v2] sh/mm/fault_32.c: Port OOM changes to do_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 the 32-bit SH platform.

Signed-off-by: Kautuk Consul <consul.kautuk@...il.com>
---
 arch/sh/mm/fault_32.c |   38 +++++++++++++++++++++++++++++---------
 1 files changed, 29 insertions(+), 9 deletions(-)

diff --git a/arch/sh/mm/fault_32.c b/arch/sh/mm/fault_32.c
index 324eef9..6084982 100644
--- a/arch/sh/mm/fault_32.c
+++ b/arch/sh/mm/fault_32.c
@@ -129,6 +129,8 @@ asmlinkage void __kprobes do_page_fault(struct pt_regs *regs,
 	int si_code;
 	int fault;
 	siginfo_t info;
+	unsigned int flags = (FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE |
+			      (writeaccess ? FAULT_FLAG_WRITE : 0));
 
 	tsk = current;
 	mm = tsk->mm;
@@ -169,6 +171,7 @@ asmlinkage void __kprobes do_page_fault(struct pt_regs *regs,
 	if (in_atomic() || !mm)
 		goto no_context;
 
+retry:
 	down_read(&mm->mmap_sem);
 
 	vma = find_vma(mm, address);
@@ -200,7 +203,11 @@ good_area:
 	 * make sure we exit gracefully rather than endlessly redo
 	 * the fault.
 	 */
-	fault = handle_mm_fault(mm, vma, address, writeaccess ? 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;
@@ -208,14 +215,27 @@ good_area:
 			goto do_sigbus;
 		BUG();
 	}
-	if (fault & VM_FAULT_MAJOR) {
-		tsk->maj_flt++;
-		perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MAJ, 1,
-				     regs, address);
-	} else {
-		tsk->min_flt++;
-		perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MIN, 1,
-				     regs, address);
+
+	if (flags & FAULT_FLAG_ALLOW_RETRY) {
+		if (fault & VM_FAULT_MAJOR) {
+			tsk->maj_flt++;
+			perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MAJ, 1,
+				      regs, address);
+		} else {
+			tsk->min_flt++;
+			perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MIN, 1,
+				      regs, address);
+		}
+		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);
-- 
1.7.5.4

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/