| Message ID | 157270779336.1961.6528158720593572480.stgit@buzz (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | mm/memcontrol: update documentation about invoking oom killer | expand |
On Sat, 02. Nov 18:16, Konstantin Khlebnikov wrote: > Since commit 29ef680ae7c2 ("memcg, oom: move out_of_memory back to the > charge path") memcg invokes oom killer not only for user page-faults. > This means 0-order allocation will either succeed or task get killed. > > Fixes: 8e675f7af507 ("mm/oom_kill: count global and memory cgroup oom kills") > Signed-off-by: Konstantin Khlebnikov <khlebnikov@yandex-team.ru> > --- > Documentation/admin-guide/cgroup-v2.rst | 9 +++++++-- > 1 file changed, 7 insertions(+), 2 deletions(-) > > diff --git a/Documentation/admin-guide/cgroup-v2.rst b/Documentation/admin-guide/cgroup-v2.rst > index 5361ebec3361..eb47815e137b 100644 > --- a/Documentation/admin-guide/cgroup-v2.rst > +++ b/Documentation/admin-guide/cgroup-v2.rst > @@ -1219,8 +1219,13 @@ PAGE_SIZE multiple when read back. > > Failed allocation in its turn could be returned into > userspace as -ENOMEM or silently ignored in cases like > - disk readahead. For now OOM in memory cgroup kills > - tasks iff shortage has happened inside page fault. > + disk readahead. > + > + Before 4.19 OOM in memory cgroup killed tasks iff Hello Konstantin, iff --> if :-) Best regards Damian > + shortage has happened inside page fault, random > + syscall may fail with ENOMEM or EFAULT. Since 4.19 > + failed memory cgroup allocation invokes oom killer and > + keeps retrying until it succeeds. > > This event is not raised if the OOM killer is not > considered as an option, e.g. for failed high-order >
On 02/11/2019 19.02, Damian Tometzki wrote: > On Sat, 02. Nov 18:16, Konstantin Khlebnikov wrote: >> Since commit 29ef680ae7c2 ("memcg, oom: move out_of_memory back to the >> charge path") memcg invokes oom killer not only for user page-faults. >> This means 0-order allocation will either succeed or task get killed. >> >> Fixes: 8e675f7af507 ("mm/oom_kill: count global and memory cgroup oom kills") >> Signed-off-by: Konstantin Khlebnikov <khlebnikov@yandex-team.ru> >> --- >> Documentation/admin-guide/cgroup-v2.rst | 9 +++++++-- >> 1 file changed, 7 insertions(+), 2 deletions(-) >> >> diff --git a/Documentation/admin-guide/cgroup-v2.rst b/Documentation/admin-guide/cgroup-v2.rst >> index 5361ebec3361..eb47815e137b 100644 >> --- a/Documentation/admin-guide/cgroup-v2.rst >> +++ b/Documentation/admin-guide/cgroup-v2.rst >> @@ -1219,8 +1219,13 @@ PAGE_SIZE multiple when read back. >> >> Failed allocation in its turn could be returned into >> userspace as -ENOMEM or silently ignored in cases like >> - disk readahead. For now OOM in memory cgroup kills >> - tasks iff shortage has happened inside page fault. >> + disk readahead. >> + >> + Before 4.19 OOM in memory cgroup killed tasks iff > Hello Konstantin, > > iff --> if :-) > This "iff" is shortened "if and only if". https://en.wikipedia.org/wiki/If_and_only_if > Best regards > Damian > > >> + shortage has happened inside page fault, random >> + syscall may fail with ENOMEM or EFAULT. Since 4.19 >> + failed memory cgroup allocation invokes oom killer and >> + keeps retrying until it succeeds. >> >> This event is not raised if the OOM killer is not >> considered as an option, e.g. for failed high-order >>
On Sat, 02. Nov 19:14, Konstantin Khlebnikov wrote: > > > On 02/11/2019 19.02, Damian Tometzki wrote: > > On Sat, 02. Nov 18:16, Konstantin Khlebnikov wrote: > >> Since commit 29ef680ae7c2 ("memcg, oom: move out_of_memory back to the > >> charge path") memcg invokes oom killer not only for user page-faults. > >> This means 0-order allocation will either succeed or task get killed. > >> > >> Fixes: 8e675f7af507 ("mm/oom_kill: count global and memory cgroup oom kills") > >> Signed-off-by: Konstantin Khlebnikov <khlebnikov@yandex-team.ru> > >> --- > >> Documentation/admin-guide/cgroup-v2.rst | 9 +++++++-- > >> 1 file changed, 7 insertions(+), 2 deletions(-) > >> > >> diff --git a/Documentation/admin-guide/cgroup-v2.rst b/Documentation/admin-guide/cgroup-v2.rst > >> index 5361ebec3361..eb47815e137b 100644 > >> --- a/Documentation/admin-guide/cgroup-v2.rst > >> +++ b/Documentation/admin-guide/cgroup-v2.rst > >> @@ -1219,8 +1219,13 @@ PAGE_SIZE multiple when read back. > >> > >> Failed allocation in its turn could be returned into > >> userspace as -ENOMEM or silently ignored in cases like > >> - disk readahead. For now OOM in memory cgroup kills > >> - tasks iff shortage has happened inside page fault. > >> + disk readahead. > >> + > >> + Before 4.19 OOM in memory cgroup killed tasks iff > > Hello Konstantin, > > > > iff --> if :-) > > > > This "iff" is shortened "if and only if". > https://en.wikipedia.org/wiki/If_and_only_if good to know :-) > > > Best regards > > Damian > > > > > >> + shortage has happened inside page fault, random > >> + syscall may fail with ENOMEM or EFAULT. Since 4.19 > >> + failed memory cgroup allocation invokes oom killer and > >> + keeps retrying until it succeeds. > >> > >> This event is not raised if the OOM killer is not > >> considered as an option, e.g. for failed high-order > >>
On Sat, 2 Nov 2019, Konstantin Khlebnikov wrote: > Since commit 29ef680ae7c2 ("memcg, oom: move out_of_memory back to the > charge path") memcg invokes oom killer not only for user page-faults. > This means 0-order allocation will either succeed or task get killed. > > Fixes: 8e675f7af507 ("mm/oom_kill: count global and memory cgroup oom kills") > Signed-off-by: Konstantin Khlebnikov <khlebnikov@yandex-team.ru> > --- > Documentation/admin-guide/cgroup-v2.rst | 9 +++++++-- > 1 file changed, 7 insertions(+), 2 deletions(-) > > diff --git a/Documentation/admin-guide/cgroup-v2.rst b/Documentation/admin-guide/cgroup-v2.rst > index 5361ebec3361..eb47815e137b 100644 > --- a/Documentation/admin-guide/cgroup-v2.rst > +++ b/Documentation/admin-guide/cgroup-v2.rst > @@ -1219,8 +1219,13 @@ PAGE_SIZE multiple when read back. > > Failed allocation in its turn could be returned into > userspace as -ENOMEM or silently ignored in cases like > - disk readahead. For now OOM in memory cgroup kills > - tasks iff shortage has happened inside page fault. > + disk readahead. > + > + Before 4.19 OOM in memory cgroup killed tasks iff > + shortage has happened inside page fault, random > + syscall may fail with ENOMEM or EFAULT. Since 4.19 > + failed memory cgroup allocation invokes oom killer and > + keeps retrying until it succeeds. > > This event is not raised if the OOM killer is not > considered as an option, e.g. for failed high-order The previous text is obviously incorrect for today's kernels, but I'm curious if we should be conflating the documentation here by describing the pre-4.19 behavior. OOM killing no longer happens only on page fault so maybe better to document the exact behavior today and not attempt to describe differences with previous versions?
On 03/11/2019 02.55, David Rientjes wrote: > On Sat, 2 Nov 2019, Konstantin Khlebnikov wrote: > >> Since commit 29ef680ae7c2 ("memcg, oom: move out_of_memory back to the >> charge path") memcg invokes oom killer not only for user page-faults. >> This means 0-order allocation will either succeed or task get killed. >> >> Fixes: 8e675f7af507 ("mm/oom_kill: count global and memory cgroup oom kills") >> Signed-off-by: Konstantin Khlebnikov <khlebnikov@yandex-team.ru> >> --- >> Documentation/admin-guide/cgroup-v2.rst | 9 +++++++-- >> 1 file changed, 7 insertions(+), 2 deletions(-) >> >> diff --git a/Documentation/admin-guide/cgroup-v2.rst b/Documentation/admin-guide/cgroup-v2.rst >> index 5361ebec3361..eb47815e137b 100644 >> --- a/Documentation/admin-guide/cgroup-v2.rst >> +++ b/Documentation/admin-guide/cgroup-v2.rst >> @@ -1219,8 +1219,13 @@ PAGE_SIZE multiple when read back. >> >> Failed allocation in its turn could be returned into >> userspace as -ENOMEM or silently ignored in cases like >> - disk readahead. For now OOM in memory cgroup kills >> - tasks iff shortage has happened inside page fault. >> + disk readahead. >> + >> + Before 4.19 OOM in memory cgroup killed tasks iff >> + shortage has happened inside page fault, random >> + syscall may fail with ENOMEM or EFAULT. Since 4.19 >> + failed memory cgroup allocation invokes oom killer and >> + keeps retrying until it succeeds. >> >> This event is not raised if the OOM killer is not >> considered as an option, e.g. for failed high-order > > The previous text is obviously incorrect for today's kernels, but I'm > curious if we should be conflating the documentation here by describing > the pre-4.19 behavior. OOM killing no longer happens only on page fault > so maybe better to document the exact behavior today and not attempt to > describe differences with previous versions? > Previous behaviour was here for ages and 4.19 is not so old. According too https://www.kernel.org/category/releases.html pre-4.19 will be maintained for couple years at least. Let's keep this tombstone. I've seen a lot of strange side effects of old behaviour. Most obscure was a hang inside libc fork() when clone(CLONE_CHILD_SETTID) silently fails to set child pid =) https://lore.kernel.org/lkml/20150206162301.18031.32251.stgit@buzz/
On Sat 02-11-19 18:16:33, Konstantin Khlebnikov wrote: > Since commit 29ef680ae7c2 ("memcg, oom: move out_of_memory back to the > charge path") memcg invokes oom killer not only for user page-faults. > This means 0-order allocation will either succeed or task get killed. > > Fixes: 8e675f7af507 ("mm/oom_kill: count global and memory cgroup oom kills") Is this really appropriate? 8e675f7af507 was correct at the time. It was 29ef680ae7c2 that hasn't updated the documentation. I would just drop the Fixes tag. > Signed-off-by: Konstantin Khlebnikov <khlebnikov@yandex-team.ru> > --- > Documentation/admin-guide/cgroup-v2.rst | 9 +++++++-- > 1 file changed, 7 insertions(+), 2 deletions(-) > > diff --git a/Documentation/admin-guide/cgroup-v2.rst b/Documentation/admin-guide/cgroup-v2.rst > index 5361ebec3361..eb47815e137b 100644 > --- a/Documentation/admin-guide/cgroup-v2.rst > +++ b/Documentation/admin-guide/cgroup-v2.rst > @@ -1219,8 +1219,13 @@ PAGE_SIZE multiple when read back. > > Failed allocation in its turn could be returned into > userspace as -ENOMEM or silently ignored in cases like > - disk readahead. For now OOM in memory cgroup kills > - tasks iff shortage has happened inside page fault. > + disk readahead. > + > + Before 4.19 OOM in memory cgroup killed tasks iff I would go with Kernels between 3.12 and 4.19 invoked the oom killer only if shortage has happened inside page fault. > + shortage has happened inside page fault, random > + syscall may fail with ENOMEM or EFAULT. Since 4.19 > + failed memory cgroup allocation invokes oom killer and > + keeps retrying until it succeeds. > > This event is not raised if the OOM killer is not > considered as an option, e.g. for failed high-order
diff --git a/Documentation/admin-guide/cgroup-v2.rst b/Documentation/admin-guide/cgroup-v2.rst index 5361ebec3361..eb47815e137b 100644 --- a/Documentation/admin-guide/cgroup-v2.rst +++ b/Documentation/admin-guide/cgroup-v2.rst @@ -1219,8 +1219,13 @@ PAGE_SIZE multiple when read back. Failed allocation in its turn could be returned into userspace as -ENOMEM or silently ignored in cases like - disk readahead. For now OOM in memory cgroup kills - tasks iff shortage has happened inside page fault. + disk readahead. + + Before 4.19 OOM in memory cgroup killed tasks iff + shortage has happened inside page fault, random + syscall may fail with ENOMEM or EFAULT. Since 4.19 + failed memory cgroup allocation invokes oom killer and + keeps retrying until it succeeds. This event is not raised if the OOM killer is not considered as an option, e.g. for failed high-order
Since commit 29ef680ae7c2 ("memcg, oom: move out_of_memory back to the charge path") memcg invokes oom killer not only for user page-faults. This means 0-order allocation will either succeed or task get killed. Fixes: 8e675f7af507 ("mm/oom_kill: count global and memory cgroup oom kills") Signed-off-by: Konstantin Khlebnikov <khlebnikov@yandex-team.ru> --- Documentation/admin-guide/cgroup-v2.rst | 9 +++++++-- 1 file changed, 7 insertions(+), 2 deletions(-)