This patch series adds a memory.reclaim proactive reclaim interface.
The rationale behind the interface and how it works are in the first
patch.
---
Changes in V4:
mm/memcontrol.c:
- Return -EINTR on signal_pending().
- On the final retry, drain percpu lru caches hoping that it might
introduce some evictable pages for reclaim.
- Simplified the retry loop as suggested by Dan Schatzberg.
selftests:
- Always return -errno on failure from cg_write() (whether open() or
write() fail), also update cg_read() and read_text() to return -errno
as well for consistency. Also make sure to correctly check that the
whole buffer was written in cg_write().
- Added a maximum number of retries for the reclaim selftest.
Changes in V3:
- Fix cg_write() (in patch 2) to properly return -1 if open() fails
and not fail if len == errno.
- Remove debug printf() in patch 3.
Changes in V2:
- Add the interface to root as well.
- Added a selftest.
- Documented the interface as a nested-keyed interface, which makes
adding optional arguments in the future easier (see doc updates in the
first patch).
- Modified the commit message to reflect changes and added a timeout
argument as a suggested possible extension
- Return -EAGAIN if the kernel fails to reclaim the full requested
amount.
---
Shakeel Butt (1):
memcg: introduce per-memcg reclaim interface
Yosry Ahmed (3):
selftests: cgroup: return -errno from cg_read()/cg_write() on failure
selftests: cgroup: fix alloc_anon_noexit() instantly freeing memory
selftests: cgroup: add a selftest for memory.reclaim
Documentation/admin-guide/cgroup-v2.rst | 21 +++++
mm/memcontrol.c | 44 +++++++++
tools/testing/selftests/cgroup/cgroup_util.c | 44 ++++-----
.../selftests/cgroup/test_memcontrol.c | 94 ++++++++++++++++++-
4 files changed, 176 insertions(+), 27 deletions(-)
--
2.36.0.rc2.479.g8af0fa9b8e-goog
Currently, cg_read()/cg_write() returns 0 on success and -1 on failure.
Modify them to return the -errno on failure.
Signed-off-by: Yosry Ahmed <[email protected]>
---
tools/testing/selftests/cgroup/cgroup_util.c | 44 +++++++++-----------
1 file changed, 19 insertions(+), 25 deletions(-)
diff --git a/tools/testing/selftests/cgroup/cgroup_util.c b/tools/testing/selftests/cgroup/cgroup_util.c
index dbaa7aabbb4a..e6f3679cdcc0 100644
--- a/tools/testing/selftests/cgroup/cgroup_util.c
+++ b/tools/testing/selftests/cgroup/cgroup_util.c
@@ -19,6 +19,7 @@
#include "cgroup_util.h"
#include "../clone3/clone3_selftests.h"
+/* Returns read len on success, or -errno on failure. */
static ssize_t read_text(const char *path, char *buf, size_t max_len)
{
ssize_t len;
@@ -26,35 +27,29 @@ static ssize_t read_text(const char *path, char *buf, size_t max_len)
fd = open(path, O_RDONLY);
if (fd < 0)
- return fd;
+ return -errno;
len = read(fd, buf, max_len - 1);
- if (len < 0)
- goto out;
- buf[len] = 0;
-out:
+ if (len >= 0)
+ buf[len] = 0;
+
close(fd);
- return len;
+ return len < 0 ? -errno : len;
}
+/* Returns written len on success, or -errno on failure. */
static ssize_t write_text(const char *path, char *buf, ssize_t len)
{
int fd;
fd = open(path, O_WRONLY | O_APPEND);
if (fd < 0)
- return fd;
+ return -errno;
len = write(fd, buf, len);
- if (len < 0) {
- close(fd);
- return len;
- }
-
close(fd);
-
- return len;
+ return len < 0 ? -errno : len;
}
char *cg_name(const char *root, const char *name)
@@ -87,16 +82,16 @@ char *cg_control(const char *cgroup, const char *control)
return ret;
}
+/* Returns 0 on success, or -errno on failure. */
int cg_read(const char *cgroup, const char *control, char *buf, size_t len)
{
char path[PATH_MAX];
+ ssize_t ret;
snprintf(path, sizeof(path), "%s/%s", cgroup, control);
- if (read_text(path, buf, len) >= 0)
- return 0;
-
- return -1;
+ ret = read_text(path, buf, len);
+ return ret >= 0 ? 0 : ret;
}
int cg_read_strcmp(const char *cgroup, const char *control,
@@ -177,17 +172,15 @@ long cg_read_lc(const char *cgroup, const char *control)
return cnt;
}
+/* Returns 0 on success, or -errno on failure. */
int cg_write(const char *cgroup, const char *control, char *buf)
{
char path[PATH_MAX];
- ssize_t len = strlen(buf);
+ ssize_t len = strlen(buf), ret;
snprintf(path, sizeof(path), "%s/%s", cgroup, control);
-
- if (write_text(path, buf, len) == len)
- return 0;
-
- return -1;
+ ret = write_text(path, buf, len);
+ return ret == len ? 0 : ret;
}
int cg_find_unified_root(char *root, size_t len)
@@ -545,7 +538,8 @@ ssize_t proc_read_text(int pid, bool thread, const char *item, char *buf, size_t
else
snprintf(path, sizeof(path), "/proc/%d/%s", pid, item);
- return read_text(path, buf, size);
+ size = read_text(path, buf, size);
+ return size < 0 ? -1 : size;
}
int proc_read_strstr(int pid, bool thread, const char *item, const char *needle)
--
2.36.0.rc2.479.g8af0fa9b8e-goog
On Thu, Apr 21, 2022 at 11:44:24PM +0000, Yosry Ahmed wrote:
> Currently, cg_read()/cg_write() returns 0 on success and -1 on failure.
> Modify them to return the -errno on failure.
>
> Signed-off-by: Yosry Ahmed <[email protected]>
Acked-by: Shakeel Butt <[email protected]>