| Message ID | 20191002234925.9190-9-vishal.l.verma@intel.com (mailing list archive) |
|---|---|
| State | Superseded |
| Commit | 43a18598f6ccffe6ae9d1d255f51b55ff84a41e5 |
| Headers | show |
| Series | fixes and movability for system-ram mode | expand |
On Wed, Oct 2, 2019 at 4:49 PM Vishal Verma <vishal.l.verma@intel.com> wrote: > > Move the note about potential races in memory onlining into the > 'Description' section to make it more prominent. Reword the note to talk > about the sources of such races, and talk about the new 'race detection' > semantics in daxctl. > > Link: https://github.com/pmem/ndctl/issues/110 > Reported-by: Ben Olson <ben.olson@intel.com> > Cc: Dan Williams <dan.j.williams@intel.com> > Signed-off-by: Vishal Verma <vishal.l.verma@intel.com> > --- > .../daxctl/daxctl-reconfigure-device.txt | 24 +++++++++++-------- > 1 file changed, 14 insertions(+), 10 deletions(-) > > diff --git a/Documentation/daxctl/daxctl-reconfigure-device.txt b/Documentation/daxctl/daxctl-reconfigure-device.txt > index 196d692..4663529 100644 > --- a/Documentation/daxctl/daxctl-reconfigure-device.txt > +++ b/Documentation/daxctl/daxctl-reconfigure-device.txt > @@ -97,6 +97,20 @@ error reconfiguring devices: Operation not supported > reconfigured 0 devices > ---- > > +'daxctl-reconfigure-device' nominally expects that it will online new memory > +blocks as 'movable', so that kernel data doesn't make it into this memory. > +However, there are other potential agents that may be configured to > +automatically online new hot-plugged memory as it appears. Most notably, > +these are the '/sys/devices/system/memory/auto_online_blocks' configuration, > +or system udev rules. If such an agent races to online memory sections, daxctl > +checks if the blocks were onlined as 'movable' memory. If this was not the > +case, and the memory blocks are found to be in a different zone, then a > +warning is displayed. If it is desired that a different agent control the > +onlining of memory blocks, and the associated memory zone, then it is > +recommended to use the --no-online option described below. This will abridge > +the device reconfiguration operation to just hotplugging the memory, and > +refrain from then onlining it. Oh here's that full description that calls out udev. I think just "See daxctl reconfigure-device --help" is sufficient for those warnings in the previous patch.
On Fri, 2019-10-18 at 13:46 -0700, Dan Williams wrote: > > > +'daxctl-reconfigure-device' nominally expects that it will online new memory > > +blocks as 'movable', so that kernel data doesn't make it into this memory. > > +However, there are other potential agents that may be configured to > > +automatically online new hot-plugged memory as it appears. Most notably, > > +these are the '/sys/devices/system/memory/auto_online_blocks' configuration, > > +or system udev rules. If such an agent races to online memory sections, daxctl > > +checks if the blocks were onlined as 'movable' memory. If this was not the > > +case, and the memory blocks are found to be in a different zone, then a > > +warning is displayed. If it is desired that a different agent control the > > +onlining of memory blocks, and the associated memory zone, then it is > > +recommended to use the --no-online option described below. This will abridge > > +the device reconfiguration operation to just hotplugging the memory, and > > +refrain from then onlining it. > > Oh here's that full description that calls out udev. > > I think just "See daxctl reconfigure-device --help" is sufficient for > those warnings in the previous patch. Yep I've truncated the runtime warning down to point here.
diff --git a/Documentation/daxctl/daxctl-reconfigure-device.txt b/Documentation/daxctl/daxctl-reconfigure-device.txt index 196d692..4663529 100644 --- a/Documentation/daxctl/daxctl-reconfigure-device.txt +++ b/Documentation/daxctl/daxctl-reconfigure-device.txt @@ -97,6 +97,20 @@ error reconfiguring devices: Operation not supported reconfigured 0 devices ---- +'daxctl-reconfigure-device' nominally expects that it will online new memory +blocks as 'movable', so that kernel data doesn't make it into this memory. +However, there are other potential agents that may be configured to +automatically online new hot-plugged memory as it appears. Most notably, +these are the '/sys/devices/system/memory/auto_online_blocks' configuration, +or system udev rules. If such an agent races to online memory sections, daxctl +checks if the blocks were onlined as 'movable' memory. If this was not the +case, and the memory blocks are found to be in a different zone, then a +warning is displayed. If it is desired that a different agent control the +onlining of memory blocks, and the associated memory zone, then it is +recommended to use the --no-online option described below. This will abridge +the device reconfiguration operation to just hotplugging the memory, and +refrain from then onlining it. + OPTIONS ------- -r:: @@ -121,16 +135,6 @@ OPTIONS brought online automatically and immediately with the 'online_movable' policy. Use this option to disable the automatic onlining behavior. - NOTE: While this option prevents daxctl from automatically onlining - the memory sections, there may be other agents, notably system udev - rules, that online new memory sections as they appear. Coordinating - with such rules is out of scope of this utility, and the system - administrator is expected to remove them if they are undesirable. - If such an agent races to online memory sections, daxctl is prepared - to lose the race, and not fail the onlining operation as it only - cares that the memory section was onlined, not that it was the one - to do so. - -f:: --force:: When converting from "system-ram" mode to "devdax", it is expected
Move the note about potential races in memory onlining into the 'Description' section to make it more prominent. Reword the note to talk about the sources of such races, and talk about the new 'race detection' semantics in daxctl. Link: https://github.com/pmem/ndctl/issues/110 Reported-by: Ben Olson <ben.olson@intel.com> Cc: Dan Williams <dan.j.williams@intel.com> Signed-off-by: Vishal Verma <vishal.l.verma@intel.com> --- .../daxctl/daxctl-reconfigure-device.txt | 24 +++++++++++-------- 1 file changed, 14 insertions(+), 10 deletions(-)