Correctable memory errors are very common on servers with large
amount of memory, and are corrected by ECC, but with two
pain points to users:
1. Correction usually happens on the fly and adds latency overhead
2. Not-fully-proved theory states excessive correctable memory
errors can develop into uncorrectable memory error.
Soft offline is kernel's additional solution for memory pages
having (excessive) corrected memory errors. Impacted page is migrated
to healthy page if it is in use, then the original page is discarded
for any future use.
The actual policy on whether (and when) to soft offline should be
maintained by userspace, especially in case of an 1G HugeTLB page.
Soft-offline dissolves the HugeTLB page, either in-use or free, into
chunks of 4K pages, reducing HugeTLB pool capacity by 1 hugepage.
If userspace has not acknowledged such behavior, it may be surprised
when later mmap hugepages MAP_FAILED due to lack of hugepages.
In case of a transparent hugepage, it will be split into 4K pages
as well; userspace will stop enjoying the transparent performance.
In addition, discarding the entire 1G HugeTLB page only because of
corrected memory errors sounds very costly and kernel better not
doing under the hood. But today there are at least 2 such cases:
1. GHES driver sees both GHES_SEV_CORRECTED and
CPER_SEC_ERROR_THRESHOLD_EXCEEDED after parsing CPER.
2. RAS Correctable Errors Collector counts correctable errors per
PFN and when the counter for a PFN reaches threshold
In both cases, userspace has no control of the soft offline performed
by kernel's memory failure recovery.
This patch series give userspace the control of softofflining any page:
kernel only soft offlines raw page / transparent hugepage / HugeTLB
hugepage if userspace has agreed to. The interface to userspace is a
new sysctl called enable_soft_offline under /proc/sys/vm. By default
enable_soft_line is 1 to preserve existing behavior in kernel.
Changelog
v1 => v2:
* incorporate feedbacks from both Miaohe Lin <linmiaohe(a)huawei.com> and
Jane Chu <jane.chu(a)oracle.com>.
* make the switch to control all pages, instead of HugeTLB specific.
* change the API from
/sys/kernel/mm/hugepages/hugepages-${size}kB/softoffline_corrected_errors
to /proc/sys/vm/enable_soft_offline.
* minor update to test code.
* update documentation of the user control API.
* v2 is based on commit 83a7eefedc9b ("Linux 6.10-rc3").
Jiaqi Yan (3):
mm/memory-failure: userspace controls soft-offlining pages
selftest/mm: test enable_soft_offline behaviors
docs: mm: add enable_soft_offline sysctl
Documentation/admin-guide/sysctl/vm.rst | 15 +
mm/memory-failure.c | 16 ++
tools/testing/selftests/mm/.gitignore | 1 +
tools/testing/selftests/mm/Makefile | 1 +
.../selftests/mm/hugetlb-soft-offline.c | 258 ++++++++++++++++++
tools/testing/selftests/mm/run_vmtests.sh | 4 +
6 files changed, 295 insertions(+)
create mode 100644 tools/testing/selftests/mm/hugetlb-soft-offline.c
--
2.45.2.505.gda0bf45e8d-goog
From: John Hubbard <jhubbard(a)nvidia.com>
[ Upstream commit cb708ab9f584f159798b60853edcf0c8b67ce295 ]
It's slightly better to set _GNU_SOURCE in the source code, but if one
must do it via the compiler invocation, then the best way to do so is
this:
$(CC) -D_GNU_SOURCE=
...because otherwise, if this form is used:
$(CC) -D_GNU_SOURCE
...then that leads the compiler to set a value, as if you had passed in:
$(CC) -D_GNU_SOURCE=1
That, in turn, leads to warnings under both gcc and clang, like this:
futex_requeue_pi.c:20: warning: "_GNU_SOURCE" redefined
Fix this by using the "-D_GNU_SOURCE=" form.
Reviewed-by: Edward Liaw <edliaw(a)google.com>
Reviewed-by: Davidlohr Bueso <dave(a)stgolabs.net>
Signed-off-by: John Hubbard <jhubbard(a)nvidia.com>
Signed-off-by: Shuah Khan <skhan(a)linuxfoundation.org>
Signed-off-by: Sasha Levin <sashal(a)kernel.org>
---
tools/testing/selftests/futex/functional/Makefile | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/tools/testing/selftests/futex/functional/Makefile b/tools/testing/selftests/futex/functional/Makefile
index a392d0917b4e5..994fa3468f170 100644
--- a/tools/testing/selftests/futex/functional/Makefile
+++ b/tools/testing/selftests/futex/functional/Makefile
@@ -1,6 +1,6 @@
# SPDX-License-Identifier: GPL-2.0
INCLUDES := -I../include -I../../ $(KHDR_INCLUDES)
-CFLAGS := $(CFLAGS) -g -O2 -Wall -D_GNU_SOURCE -pthread $(INCLUDES) $(KHDR_INCLUDES)
+CFLAGS := $(CFLAGS) -g -O2 -Wall -D_GNU_SOURCE= -pthread $(INCLUDES) $(KHDR_INCLUDES)
LDLIBS := -lpthread -lrt
LOCAL_HDRS := \
--
2.43.0
From: John Hubbard <jhubbard(a)nvidia.com>
[ Upstream commit cb708ab9f584f159798b60853edcf0c8b67ce295 ]
It's slightly better to set _GNU_SOURCE in the source code, but if one
must do it via the compiler invocation, then the best way to do so is
this:
$(CC) -D_GNU_SOURCE=
...because otherwise, if this form is used:
$(CC) -D_GNU_SOURCE
...then that leads the compiler to set a value, as if you had passed in:
$(CC) -D_GNU_SOURCE=1
That, in turn, leads to warnings under both gcc and clang, like this:
futex_requeue_pi.c:20: warning: "_GNU_SOURCE" redefined
Fix this by using the "-D_GNU_SOURCE=" form.
Reviewed-by: Edward Liaw <edliaw(a)google.com>
Reviewed-by: Davidlohr Bueso <dave(a)stgolabs.net>
Signed-off-by: John Hubbard <jhubbard(a)nvidia.com>
Signed-off-by: Shuah Khan <skhan(a)linuxfoundation.org>
Signed-off-by: Sasha Levin <sashal(a)kernel.org>
---
tools/testing/selftests/futex/functional/Makefile | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/tools/testing/selftests/futex/functional/Makefile b/tools/testing/selftests/futex/functional/Makefile
index a392d0917b4e5..994fa3468f170 100644
--- a/tools/testing/selftests/futex/functional/Makefile
+++ b/tools/testing/selftests/futex/functional/Makefile
@@ -1,6 +1,6 @@
# SPDX-License-Identifier: GPL-2.0
INCLUDES := -I../include -I../../ $(KHDR_INCLUDES)
-CFLAGS := $(CFLAGS) -g -O2 -Wall -D_GNU_SOURCE -pthread $(INCLUDES) $(KHDR_INCLUDES)
+CFLAGS := $(CFLAGS) -g -O2 -Wall -D_GNU_SOURCE= -pthread $(INCLUDES) $(KHDR_INCLUDES)
LDLIBS := -lpthread -lrt
LOCAL_HDRS := \
--
2.43.0
From: John Hubbard <jhubbard(a)nvidia.com>
[ Upstream commit cb708ab9f584f159798b60853edcf0c8b67ce295 ]
It's slightly better to set _GNU_SOURCE in the source code, but if one
must do it via the compiler invocation, then the best way to do so is
this:
$(CC) -D_GNU_SOURCE=
...because otherwise, if this form is used:
$(CC) -D_GNU_SOURCE
...then that leads the compiler to set a value, as if you had passed in:
$(CC) -D_GNU_SOURCE=1
That, in turn, leads to warnings under both gcc and clang, like this:
futex_requeue_pi.c:20: warning: "_GNU_SOURCE" redefined
Fix this by using the "-D_GNU_SOURCE=" form.
Reviewed-by: Edward Liaw <edliaw(a)google.com>
Reviewed-by: Davidlohr Bueso <dave(a)stgolabs.net>
Signed-off-by: John Hubbard <jhubbard(a)nvidia.com>
Signed-off-by: Shuah Khan <skhan(a)linuxfoundation.org>
Signed-off-by: Sasha Levin <sashal(a)kernel.org>
---
tools/testing/selftests/futex/functional/Makefile | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/tools/testing/selftests/futex/functional/Makefile b/tools/testing/selftests/futex/functional/Makefile
index a392d0917b4e5..994fa3468f170 100644
--- a/tools/testing/selftests/futex/functional/Makefile
+++ b/tools/testing/selftests/futex/functional/Makefile
@@ -1,6 +1,6 @@
# SPDX-License-Identifier: GPL-2.0
INCLUDES := -I../include -I../../ $(KHDR_INCLUDES)
-CFLAGS := $(CFLAGS) -g -O2 -Wall -D_GNU_SOURCE -pthread $(INCLUDES) $(KHDR_INCLUDES)
+CFLAGS := $(CFLAGS) -g -O2 -Wall -D_GNU_SOURCE= -pthread $(INCLUDES) $(KHDR_INCLUDES)
LDLIBS := -lpthread -lrt
LOCAL_HDRS := \
--
2.43.0
From: Michael Ellerman <mpe(a)ellerman.id.au>
[ Upstream commit e8b8c5264d4ebd248f60a5cef077fe615806e7a0 ]
Fix build error on ppc64:
dev_in_maps.c: In function ‘get_file_dev_and_inode’:
dev_in_maps.c:60:59: error: format ‘%llu’ expects argument of type
‘long long unsigned int *’, but argument 7 has type ‘__u64 *’ {aka ‘long
unsigned int *’} [-Werror=format=]
By switching to unsigned long long for u64 for ppc64 builds.
Signed-off-by: Michael Ellerman <mpe(a)ellerman.id.au>
Signed-off-by: Shuah Khan <skhan(a)linuxfoundation.org>
Signed-off-by: Sasha Levin <sashal(a)kernel.org>
---
tools/testing/selftests/filesystems/overlayfs/dev_in_maps.c | 1 +
1 file changed, 1 insertion(+)
diff --git a/tools/testing/selftests/filesystems/overlayfs/dev_in_maps.c b/tools/testing/selftests/filesystems/overlayfs/dev_in_maps.c
index 759f86e7d263e..2862aae58b79a 100644
--- a/tools/testing/selftests/filesystems/overlayfs/dev_in_maps.c
+++ b/tools/testing/selftests/filesystems/overlayfs/dev_in_maps.c
@@ -1,5 +1,6 @@
// SPDX-License-Identifier: GPL-2.0
#define _GNU_SOURCE
+#define __SANE_USERSPACE_TYPES__ // Use ll64
#include <inttypes.h>
#include <unistd.h>
--
2.43.0