| Message ID | 20230704115240.14672-1-mhocko@kernel.org (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | memcg: drop kmem.limit_in_bytes | expand |
On Tue, Jul 04, 2023 at 01:52:40PM +0200, Michal Hocko wrote: > From: Michal Hocko <mhocko@suse.com> > > kmem.limit_in_bytes (v1 way to limit kernel memory usage) has been > deprecated since 58056f77502f ("memcg, kmem: further deprecate > kmem.limit_in_bytes") merged in 5.16. We haven't heard about any > serious users since then but it seems that the mere presence of the file > is causing more harm thatn good. We (SUSE) have had several bug reports > from customers where Docker based containers started to fail because a > write to kmem.limit_in_bytes has failed. > > This was unexpected because runc code only expects ENOENT (kmem > disabled) or EBUSY (tasks already running within cgroup). So a new error > code was unexpected and the whole container startup failed. This has > been later addressed by > https://github.com/opencontainers/runc/commit/52390d68040637dfc77f9fda6bbe70952423d380 > so current Docker runtimes do not suffer from the problem anymore. There > are still older version of Docker in use and likely hard to get rid of > completely. > > Address this by wiping out the file completely and effectively get back > to pre 4.5 era and CONFIG_MEMCG_KMEM=n configuration. > > I would recommend backporting to stable trees which have picked up > 58056f77502f ("memcg, kmem: further deprecate kmem.limit_in_bytes"). > > Cc: stable > Signed-off-by: Michal Hocko <mhocko@suse.com> Acked-by: Shakeel Butt <shakeelb@google.com>
On Tue, Jul 04, 2023 at 01:52:40PM +0200, Michal Hocko wrote: > From: Michal Hocko <mhocko@suse.com> > > kmem.limit_in_bytes (v1 way to limit kernel memory usage) has been > deprecated since 58056f77502f ("memcg, kmem: further deprecate > kmem.limit_in_bytes") merged in 5.16. We haven't heard about any > serious users since then but it seems that the mere presence of the file > is causing more harm thatn good. We (SUSE) have had several bug reports > from customers where Docker based containers started to fail because a > write to kmem.limit_in_bytes has failed. > > This was unexpected because runc code only expects ENOENT (kmem > disabled) or EBUSY (tasks already running within cgroup). So a new error > code was unexpected and the whole container startup failed. This has > been later addressed by > https://github.com/opencontainers/runc/commit/52390d68040637dfc77f9fda6bbe70952423d380 > so current Docker runtimes do not suffer from the problem anymore. There > are still older version of Docker in use and likely hard to get rid of > completely. > > Address this by wiping out the file completely and effectively get back > to pre 4.5 era and CONFIG_MEMCG_KMEM=n configuration. > > I would recommend backporting to stable trees which have picked up > 58056f77502f ("memcg, kmem: further deprecate kmem.limit_in_bytes"). > > Cc: stable > Signed-off-by: Michal Hocko <mhocko@suse.com> > --- > Documentation/admin-guide/cgroup-v1/memory.rst | 2 -- > mm/memcontrol.c | 13 ------------- > 2 files changed, 15 deletions(-) > > diff --git a/Documentation/admin-guide/cgroup-v1/memory.rst b/Documentation/admin-guide/cgroup-v1/memory.rst > index 47d1d7d932a8..b92c71f39172 100644 > --- a/Documentation/admin-guide/cgroup-v1/memory.rst > +++ b/Documentation/admin-guide/cgroup-v1/memory.rst > @@ -92,8 +92,6 @@ Brief summary of control files. > memory.oom_control set/show oom controls. > memory.numa_stat show the number of memory usage per numa > node > - memory.kmem.limit_in_bytes This knob is deprecated and writing to > - it will return -ENOTSUPP. > memory.kmem.usage_in_bytes show current kernel memory allocation > memory.kmem.failcnt show the number of kernel memory usage > hits limits > diff --git a/mm/memcontrol.c b/mm/memcontrol.c > index 4b27e245a055..a0d3ed8d02e2 100644 > --- a/mm/memcontrol.c > +++ b/mm/memcontrol.c > @@ -3750,9 +3750,6 @@ static u64 mem_cgroup_read_u64(struct cgroup_subsys_state *css, > case _MEMSWAP: > counter = &memcg->memsw; > break; > - case _KMEM: > - counter = &memcg->kmem; > - break; > case _TCP: > counter = &memcg->tcpmem; > break; This case is still needed for the remaining kmem files: { .name = "kmem.usage_in_bytes", .private = MEMFILE_PRIVATE(_KMEM, RES_USAGE), .read_u64 = mem_cgroup_read_u64, }, { .name = "kmem.failcnt", .private = MEMFILE_PRIVATE(_KMEM, RES_FAILCNT), .write = mem_cgroup_reset, .read_u64 = mem_cgroup_read_u64, }, { .name = "kmem.max_usage_in_bytes", .private = MEMFILE_PRIVATE(_KMEM, RES_MAX_USAGE), .write = mem_cgroup_reset, .read_u64 = mem_cgroup_read_u64, }, otherwise they BUG() when reading. Without this hunk, the patch looks good to me.
On Wed 05-07-23 09:44:34, Johannes Weiner wrote: [...] > > diff --git a/mm/memcontrol.c b/mm/memcontrol.c > > index 4b27e245a055..a0d3ed8d02e2 100644 > > --- a/mm/memcontrol.c > > +++ b/mm/memcontrol.c > > @@ -3750,9 +3750,6 @@ static u64 mem_cgroup_read_u64(struct cgroup_subsys_state *css, > > case _MEMSWAP: > > counter = &memcg->memsw; > > break; > > - case _KMEM: > > - counter = &memcg->kmem; > > - break; > > case _TCP: > > counter = &memcg->tcpmem; > > break; > > This case is still needed for the remaining kmem files: > > { > .name = "kmem.usage_in_bytes", > .private = MEMFILE_PRIVATE(_KMEM, RES_USAGE), > .read_u64 = mem_cgroup_read_u64, > }, > { > .name = "kmem.failcnt", > .private = MEMFILE_PRIVATE(_KMEM, RES_FAILCNT), > .write = mem_cgroup_reset, > .read_u64 = mem_cgroup_read_u64, > }, > { > .name = "kmem.max_usage_in_bytes", > .private = MEMFILE_PRIVATE(_KMEM, RES_MAX_USAGE), > .write = mem_cgroup_reset, > .read_u64 = mem_cgroup_read_u64, > }, > > otherwise they BUG() when reading. > > Without this hunk, the patch looks good to me. You are right! Thanks. The updated patch below. Andrew could you replace by this version please? --- From b1bbc63b6baff9c5aaf30393cec29112b3abca25 Mon Sep 17 00:00:00 2001 From: Michal Hocko <mhocko@suse.com> Date: Tue, 4 Jul 2023 13:38:11 +0200 Subject: [PATCH] memcg: drop kmem.limit_in_bytes kmem.limit_in_bytes (v1 way to limit kernel memory usage) has been deprecated since 58056f77502f ("memcg, kmem: further deprecate kmem.limit_in_bytes") merged in 5.16. We haven't heard about any serious users since then but it seems that the mere presence of the file is causing more harm thatn good. We (SUSE) have had several bug reports from customers where Docker based containers started to fail because a write to kmem.limit_in_bytes has failed. This was unexpected because runc code only expects ENOENT (kmem disabled) or EBUSY (tasks already running within cgroup). So a new error code was unexpected and the whole container startup failed. This has been later addressed by https://github.com/opencontainers/runc/commit/52390d68040637dfc77f9fda6bbe70952423d380 so current Docker runtimes do not suffer from the problem anymore. There are still older version of Docker in use and likely hard to get rid of completely. Address this by wiping out the file completely and effectively get back to pre 4.5 era and CONFIG_MEMCG_KMEM=n configuration. I would recommend backporting to stable trees which have picked up 58056f77502f ("memcg, kmem: further deprecate kmem.limit_in_bytes"). Cc: stable Signed-off-by: Michal Hocko <mhocko@suse.com> --- Documentation/admin-guide/cgroup-v1/memory.rst | 2 -- mm/memcontrol.c | 10 ---------- 2 files changed, 12 deletions(-) diff --git a/Documentation/admin-guide/cgroup-v1/memory.rst b/Documentation/admin-guide/cgroup-v1/memory.rst index fabaad3fd9c2..8d3afeede10e 100644 --- a/Documentation/admin-guide/cgroup-v1/memory.rst +++ b/Documentation/admin-guide/cgroup-v1/memory.rst @@ -92,8 +92,6 @@ Brief summary of control files. memory.oom_control set/show oom controls. memory.numa_stat show the number of memory usage per numa node - memory.kmem.limit_in_bytes This knob is deprecated and writing to - it will return -ENOTSUPP. memory.kmem.usage_in_bytes show current kernel memory allocation memory.kmem.failcnt show the number of kernel memory usage hits limits diff --git a/mm/memcontrol.c b/mm/memcontrol.c index e8ca4bdcb03c..ab99503c9ff2 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -3871,10 +3871,6 @@ static ssize_t mem_cgroup_write(struct kernfs_open_file *of, case _MEMSWAP: ret = mem_cgroup_resize_max(memcg, nr_pages, true); break; - case _KMEM: - /* kmem.limit_in_bytes is deprecated. */ - ret = -EOPNOTSUPP; - break; case _TCP: ret = memcg_update_tcp_max(memcg, nr_pages); break; @@ -5085,12 +5081,6 @@ static struct cftype mem_cgroup_legacy_files[] = { .seq_show = memcg_numa_stat_show, }, #endif - { - .name = "kmem.limit_in_bytes", - .private = MEMFILE_PRIVATE(_KMEM, RES_LIMIT), - .write = mem_cgroup_write, - .read_u64 = mem_cgroup_read_u64, - }, { .name = "kmem.usage_in_bytes", .private = MEMFILE_PRIVATE(_KMEM, RES_USAGE),
On Fri, Jul 07, 2023 at 09:07:47AM +0200, Michal Hocko wrote: > From b1bbc63b6baff9c5aaf30393cec29112b3abca25 Mon Sep 17 00:00:00 2001 > From: Michal Hocko <mhocko@suse.com> > Date: Tue, 4 Jul 2023 13:38:11 +0200 > Subject: [PATCH] memcg: drop kmem.limit_in_bytes > > kmem.limit_in_bytes (v1 way to limit kernel memory usage) has been > deprecated since 58056f77502f ("memcg, kmem: further deprecate > kmem.limit_in_bytes") merged in 5.16. We haven't heard about any > serious users since then but it seems that the mere presence of the file > is causing more harm thatn good. We (SUSE) have had several bug reports > from customers where Docker based containers started to fail because a > write to kmem.limit_in_bytes has failed. > > This was unexpected because runc code only expects ENOENT (kmem > disabled) or EBUSY (tasks already running within cgroup). So a new error > code was unexpected and the whole container startup failed. This has > been later addressed by > https://github.com/opencontainers/runc/commit/52390d68040637dfc77f9fda6bbe70952423d380 > so current Docker runtimes do not suffer from the problem anymore. There > are still older version of Docker in use and likely hard to get rid of > completely. > > Address this by wiping out the file completely and effectively get back > to pre 4.5 era and CONFIG_MEMCG_KMEM=n configuration. > > I would recommend backporting to stable trees which have picked up > 58056f77502f ("memcg, kmem: further deprecate kmem.limit_in_bytes"). > > Cc: stable > Signed-off-by: Michal Hocko <mhocko@suse.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org>
On Fri, Jul 07, 2023 at 09:07:47AM +0200, Michal Hocko wrote: > On Wed 05-07-23 09:44:34, Johannes Weiner wrote: > [...] > > > diff --git a/mm/memcontrol.c b/mm/memcontrol.c > > > index 4b27e245a055..a0d3ed8d02e2 100644 > > > --- a/mm/memcontrol.c > > > +++ b/mm/memcontrol.c > > > @@ -3750,9 +3750,6 @@ static u64 mem_cgroup_read_u64(struct cgroup_subsys_state *css, > > > case _MEMSWAP: > > > counter = &memcg->memsw; > > > break; > > > - case _KMEM: > > > - counter = &memcg->kmem; > > > - break; > > > case _TCP: > > > counter = &memcg->tcpmem; > > > break; > > > > This case is still needed for the remaining kmem files: > > > > { > > .name = "kmem.usage_in_bytes", > > .private = MEMFILE_PRIVATE(_KMEM, RES_USAGE), > > .read_u64 = mem_cgroup_read_u64, > > }, > > { > > .name = "kmem.failcnt", > > .private = MEMFILE_PRIVATE(_KMEM, RES_FAILCNT), > > .write = mem_cgroup_reset, > > .read_u64 = mem_cgroup_read_u64, > > }, > > { > > .name = "kmem.max_usage_in_bytes", > > .private = MEMFILE_PRIVATE(_KMEM, RES_MAX_USAGE), > > .write = mem_cgroup_reset, > > .read_u64 = mem_cgroup_read_u64, > > }, > > > > otherwise they BUG() when reading. > > > > Without this hunk, the patch looks good to me. > > You are right! Thanks. The updated patch below. Andrew could you replace > by this version please? > --- > From b1bbc63b6baff9c5aaf30393cec29112b3abca25 Mon Sep 17 00:00:00 2001 > From: Michal Hocko <mhocko@suse.com> > Date: Tue, 4 Jul 2023 13:38:11 +0200 > Subject: [PATCH] memcg: drop kmem.limit_in_bytes > > kmem.limit_in_bytes (v1 way to limit kernel memory usage) has been > deprecated since 58056f77502f ("memcg, kmem: further deprecate > kmem.limit_in_bytes") merged in 5.16. We haven't heard about any > serious users since then but it seems that the mere presence of the file > is causing more harm thatn good. We (SUSE) have had several bug reports > from customers where Docker based containers started to fail because a > write to kmem.limit_in_bytes has failed. > > This was unexpected because runc code only expects ENOENT (kmem > disabled) or EBUSY (tasks already running within cgroup). So a new error > code was unexpected and the whole container startup failed. This has > been later addressed by > https://github.com/opencontainers/runc/commit/52390d68040637dfc77f9fda6bbe70952423d380 > so current Docker runtimes do not suffer from the problem anymore. There > are still older version of Docker in use and likely hard to get rid of > completely. > > Address this by wiping out the file completely and effectively get back > to pre 4.5 era and CONFIG_MEMCG_KMEM=n configuration. > > I would recommend backporting to stable trees which have picked up > 58056f77502f ("memcg, kmem: further deprecate kmem.limit_in_bytes"). > > Cc: stable > Signed-off-by: Michal Hocko <mhocko@suse.com> Acked-by: Roman Gushchin <roman.gushchin@linux.dev> Thanks!
diff --git a/Documentation/admin-guide/cgroup-v1/memory.rst b/Documentation/admin-guide/cgroup-v1/memory.rst index 47d1d7d932a8..b92c71f39172 100644 --- a/Documentation/admin-guide/cgroup-v1/memory.rst +++ b/Documentation/admin-guide/cgroup-v1/memory.rst @@ -92,8 +92,6 @@ Brief summary of control files. memory.oom_control set/show oom controls. memory.numa_stat show the number of memory usage per numa node - memory.kmem.limit_in_bytes This knob is deprecated and writing to - it will return -ENOTSUPP. memory.kmem.usage_in_bytes show current kernel memory allocation memory.kmem.failcnt show the number of kernel memory usage hits limits diff --git a/mm/memcontrol.c b/mm/memcontrol.c index 4b27e245a055..a0d3ed8d02e2 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -3750,9 +3750,6 @@ static u64 mem_cgroup_read_u64(struct cgroup_subsys_state *css, case _MEMSWAP: counter = &memcg->memsw; break; - case _KMEM: - counter = &memcg->kmem; - break; case _TCP: counter = &memcg->tcpmem; break; @@ -3913,10 +3910,6 @@ static ssize_t mem_cgroup_write(struct kernfs_open_file *of, case _MEMSWAP: ret = mem_cgroup_resize_max(memcg, nr_pages, true); break; - case _KMEM: - /* kmem.limit_in_bytes is deprecated. */ - ret = -EOPNOTSUPP; - break; case _TCP: ret = memcg_update_tcp_max(memcg, nr_pages); break; @@ -5132,12 +5125,6 @@ static struct cftype mem_cgroup_legacy_files[] = { .seq_show = memcg_numa_stat_show, }, #endif - { - .name = "kmem.limit_in_bytes", - .private = MEMFILE_PRIVATE(_KMEM, RES_LIMIT), - .write = mem_cgroup_write, - .read_u64 = mem_cgroup_read_u64, - }, { .name = "kmem.usage_in_bytes", .private = MEMFILE_PRIVATE(_KMEM, RES_USAGE),