incoming

incoming

[Andrew Morton]

4 patches, based on 56e337f2cf1326323844927a04e9dbce9a244835.

Subsystems affected by this patch series:

  mm/swap
  kconfig
  ocfs2
  selftests

Subsystem: mm/swap

    Guo Ziliang <guo.ziliang@zte.com.cn>:
      mm: swap: get rid of deadloop in swapin readahead

Subsystem: kconfig

    Qian Cai <quic_qiancai@quicinc.com>:
      configs/debug: restore DEBUG_INFO=y for overriding

Subsystem: ocfs2

    Joseph Qi <joseph.qi@linux.alibaba.com>:
      ocfs2: fix crash when initialize filecheck kobj fails

Subsystem: selftests

    Yosry Ahmed <yosryahmed@google.com>:
      selftests: vm: fix clang build error multiple output files

 fs/ocfs2/super.c                    |   22 +++++++++++-----------
 kernel/configs/debug.config         |    1 +
 mm/swap_state.c                     |    2 +-
 tools/testing/selftests/vm/Makefile |    6 ++----
 4 files changed, 15 insertions(+), 16 deletions(-)

[patch 1/4] mm: swap: get rid of deadloop in swapin readahead

[Andrew Morton]

From: Guo Ziliang <guo.ziliang@zte.com.cn>
Subject: mm: swap: get rid of deadloop in swapin readahead

In our testing, a deadloop task was found.  Through sysrq printing, same
stack was found every time, as follows:

__swap_duplicate+0x58/0x1a0
swapcache_prepare+0x24/0x30
__read_swap_cache_async+0xac/0x220
read_swap_cache_async+0x58/0xa0
swapin_readahead+0x24c/0x628
do_swap_page+0x374/0x8a0
__handle_mm_fault+0x598/0xd60
handle_mm_fault+0x114/0x200
do_page_fault+0x148/0x4d0
do_translation_fault+0xb0/0xd4
do_mem_abort+0x50/0xb0

The reason for the deadloop is that swapcache_prepare() always returns
EEXIST, indicating that SWAP_HAS_CACHE has not been cleared, so that it
cannot jump out of the loop.  We suspect that the task that clears the
SWAP_HAS_CACHE flag never gets a chance to run.  We try to lower the
priority of the task stuck in a deadloop so that the task that clears the
SWAP_HAS_CACHE flag will run.  The results show that the system returns to
normal after the priority is lowered.

In our testing, multiple real-time tasks are bound to the same core, and
the task in the deadloop is the highest priority task of the core, so the
deadloop task cannot be preempted.

Although cond_resched() is used by __read_swap_cache_async, it is an empty
function in the preemptive system and cannot achieve the purpose of
releasing the CPU.  A high-priority task cannot release the CPU unless
preempted by a higher-priority task.  But when this task is already the
highest priority task on this core, other tasks will not be able to be
scheduled.  So we think we should replace cond_resched() with
schedule_timeout_uninterruptible(1), schedule_timeout_interruptible will
call set_current_state first to set the task state, so the task will be
removed from the running queue, so as to achieve the purpose of giving up
the CPU and prevent it from running in kernel mode for too long.

(akpm: ugly hack becomes uglier.  But it fixes the issue in a
backportable-to-stable fashion while we hopefully work on something
better)

Link: https://lkml.kernel.org/r/20220221111749.1928222-1-cgel.zte@gmail.com
Signed-off-by: Guo Ziliang <guo.ziliang@zte.com.cn>
Reported-by: Zeal Robot <zealci@zte.com.cn>
Reviewed-by: Ran Xiaokai <ran.xiaokai@zte.com.cn>
Reviewed-by: Jiang Xuexin <jiang.xuexin@zte.com.cn>
Reviewed-by: Yang Yang <yang.yang29@zte.com.cn>
Acked-by: Hugh Dickins <hughd@google.com>
Cc: Naoya Horiguchi <naoya.horiguchi@nec.com>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Roger Quadros <rogerq@kernel.org>
Cc: Ziliang Guo <guo.ziliang@zte.com.cn>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 mm/swap_state.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/mm/swap_state.c~mm-swap-get-rid-of-deadloop-in-swapin-readahead
+++ a/mm/swap_state.c
@@ -478,7 +478,7 @@ struct page *__read_swap_cache_async(swp
 		 * __read_swap_cache_async(), which has set SWAP_HAS_CACHE
 		 * in swap_map, but not yet added its page to swap cache.
 		 */
-		cond_resched();
+		schedule_timeout_uninterruptible(1);
 	}
 
 	/*
_

[patch 2/4] configs/debug: restore DEBUG_INFO=y for overriding

[Andrew Morton]

From: Qian Cai <quic_qiancai@quicinc.com>
Subject: configs/debug: restore DEBUG_INFO=y for overriding

Previously, I failed to realize that Kees' patch [1] has not been merged
into the mainline yet, and dropped DEBUG_INFO=y too eagerly from the
mainline.  As the results, "make debug.config" won't be able to flip
DEBUG_INFO=n from the existing .config.  This should close the gaps of a
few weeks before Kees' patch is there, and work regardless of their
merging status anyway.

[1] https://lore.kernel.org/all/20220125075126.891825-1-keescook@chromium.org/

Link: https://lkml.kernel.org/r/20220308153524.8618-1-quic_qiancai@quicinc.com
Signed-off-by: Qian Cai <quic_qiancai@quicinc.com>
Reported-by: Daniel Thompson <daniel.thompson@linaro.org>
Reviewed-by: Daniel Thompson <daniel.thompson@linaro.org>
Cc: Kees Cook <keescook@chromium.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 kernel/configs/debug.config |    1 +
 1 file changed, 1 insertion(+)

--- a/kernel/configs/debug.config~configs-debug-restore-debug_info=y-for-overriding
+++ a/kernel/configs/debug.config
@@ -16,6 +16,7 @@ CONFIG_SYMBOLIC_ERRNAME=y
 #
 # Compile-time checks and compiler options
 #
+CONFIG_DEBUG_INFO=y
 CONFIG_DEBUG_INFO_DWARF_TOOLCHAIN_DEFAULT=y
 CONFIG_DEBUG_SECTION_MISMATCH=y
 CONFIG_FRAME_WARN=2048
_

[patch 3/4] ocfs2: fix crash when initialize filecheck kobj fails

[Andrew Morton]

From: Joseph Qi <joseph.qi@linux.alibaba.com>
Subject: ocfs2: fix crash when initialize filecheck kobj fails

Once s_root is set, genric_shutdown_super() will be called if fill_super()
fails.  That means, we will call ocfs2_dismount_volume() twice in such
case, which can lead to kernel crash.  Fix this issue by initializing
filecheck kobj before setting s_root.

Link: https://lkml.kernel.org/r/20220310081930.86305-1-joseph.qi@linux.alibaba.com
Fixes: 5f483c4abb50 ("ocfs2: add kobject for online file check")
Signed-off-by: Joseph Qi <joseph.qi@linux.alibaba.com>
Cc: Mark Fasheh <mark@fasheh.com>
Cc: Joel Becker <jlbec@evilplan.org>
Cc: Junxiao Bi <junxiao.bi@oracle.com>
Cc: Changwei Ge <gechangwei@live.cn>
Cc: Gang He <ghe@suse.com>
Cc: Jun Piao <piaojun@huawei.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 fs/ocfs2/super.c |   22 +++++++++++-----------
 1 file changed, 11 insertions(+), 11 deletions(-)

--- a/fs/ocfs2/super.c~ocfs2-fix-crash-when-initialize-filecheck-kobj-fails
+++ a/fs/ocfs2/super.c
@@ -1105,17 +1105,6 @@ static int ocfs2_fill_super(struct super
 		goto read_super_error;
 	}
 
-	root = d_make_root(inode);
-	if (!root) {
-		status = -ENOMEM;
-		mlog_errno(status);
-		goto read_super_error;
-	}
-
-	sb->s_root = root;
-
-	ocfs2_complete_mount_recovery(osb);
-
 	osb->osb_dev_kset = kset_create_and_add(sb->s_id, NULL,
 						&ocfs2_kset->kobj);
 	if (!osb->osb_dev_kset) {
@@ -1133,6 +1122,17 @@ static int ocfs2_fill_super(struct super
 		goto read_super_error;
 	}
 
+	root = d_make_root(inode);
+	if (!root) {
+		status = -ENOMEM;
+		mlog_errno(status);
+		goto read_super_error;
+	}
+
+	sb->s_root = root;
+
+	ocfs2_complete_mount_recovery(osb);
+
 	if (ocfs2_mount_local(osb))
 		snprintf(nodestr, sizeof(nodestr), "local");
 	else
_

[patch 4/4] selftests: vm: fix clang build error multiple output files

[Andrew Morton]

From: Yosry Ahmed <yosryahmed@google.com>
Subject: selftests: vm: fix clang build error multiple output files

When building the vm selftests using clang, some errors are seen due to
having headers in the compilation command:

clang -Wall -I ../../../../usr/include  -no-pie    gup_test.c ../../../../mm/gup_test.h -lrt -lpthread -o .../tools/testing/selftests/vm/gup_test
clang: error: cannot specify -o when generating multiple output files
make[1]: *** [../lib.mk:146: .../tools/testing/selftests/vm/gup_test] Error 1

Rework to add the header files to LOCAL_HDRS before including ../lib.mk,
since the dependency is evaluated in '$(OUTPUT)/%:%.c $(LOCAL_HDRS)' in
file lib.mk.

Link: https://lkml.kernel.org/r/20220304000645.1888133-1-yosryahmed@google.com
Signed-off-by: Yosry Ahmed <yosryahmed@google.com>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Nathan Chancellor <nathan@kernel.org>
Cc: Nick Desaulniers <ndesaulniers@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 tools/testing/selftests/vm/Makefile |    6 ++----
 1 file changed, 2 insertions(+), 4 deletions(-)

--- a/tools/testing/selftests/vm/Makefile~selftests-vm-fix-clang-build-error-multiple-output-files
+++ a/tools/testing/selftests/vm/Makefile
@@ -1,6 +1,8 @@
 # SPDX-License-Identifier: GPL-2.0
 # Makefile for vm selftests
 
+LOCAL_HDRS += $(selfdir)/vm/local_config.h $(top_srcdir)/mm/gup_test.h
+
 include local_config.mk
 
 uname_M := $(shell uname -m 2>/dev/null || echo not)
@@ -140,10 +142,6 @@ endif
 
 $(OUTPUT)/mlock-random-test $(OUTPUT)/memfd_secret: LDLIBS += -lcap
 
-$(OUTPUT)/gup_test: ../../../../mm/gup_test.h
-
-$(OUTPUT)/hmm-tests: local_config.h
-
 # HMM_EXTRA_LIBS may get set in local_config.mk, or it may be left empty.
 $(OUTPUT)/hmm-tests: LDLIBS += $(HMM_EXTRA_LIBS)
 
_