search for: hotremove

...eed. > >I think you should start with simple approach and impove incrementally > >if this turns out to be not optimal. I really detest taking struct pages > >outside of the lock. You never know what might happen after the lock is > >dropped. E.g. can you race with the memory hotremove? > > > The caller won't use pages returned from the function, so I think there > shouldn't be an issue or race if the returned pages are used (i.e. not free > anymore) or simply gone due to hotremove. No, this is just too error prone. Consider that struct page pointer itse...

...eed. > >I think you should start with simple approach and impove incrementally > >if this turns out to be not optimal. I really detest taking struct pages > >outside of the lock. You never know what might happen after the lock is > >dropped. E.g. can you race with the memory hotremove? > > > The caller won't use pages returned from the function, so I think there > shouldn't be an issue or race if the returned pages are used (i.e. not free > anymore) or simply gone due to hotremove. No, this is just too error prone. Consider that struct page pointer itse...

...s of the performance that we > need. I think you should start with simple approach and impove incrementally if this turns out to be not optimal. I really detest taking struct pages outside of the lock. You never know what might happen after the lock is dropped. E.g. can you race with the memory hotremove? > The struct page is used as a "state" to get the next free page block. It is > only > given for an internal implementation of a function in mm ( not seen by the > outside caller). Would this be OK? > If not, how about pfn - we can also pass in pfn to the function, and do...

...s of the performance that we > need. I think you should start with simple approach and impove incrementally if this turns out to be not optimal. I really detest taking struct pages outside of the lock. You never know what might happen after the lock is dropped. E.g. can you race with the memory hotremove? > The struct page is used as a "state" to get the next free page block. It is > only > given for an internal implementation of a function in mm ( not seen by the > outside caller). Would this be OK? > If not, how about pfn - we can also pass in pfn to the function, and do...

...u should start with simple approach and impove incrementally > >>>if this turns out to be not optimal. I really detest taking struct pages > >>>outside of the lock. You never know what might happen after the lock is > >>>dropped. E.g. can you race with the memory hotremove? > >> > >>The caller won't use pages returned from the function, so I think there > >>shouldn't be an issue or race if the returned pages are used (i.e. not free > >>anymore) or simply gone due to hotremove. > >No, this is just too error prone. Cons...

...u should start with simple approach and impove incrementally > >>>if this turns out to be not optimal. I really detest taking struct pages > >>>outside of the lock. You never know what might happen after the lock is > >>>dropped. E.g. can you race with the memory hotremove? > >> > >>The caller won't use pages returned from the function, so I think there > >>shouldn't be an issue or race if the returned pages are used (i.e. not free > >>anymore) or simply gone due to hotremove. > >No, this is just too error prone. Cons...

I got the email that a drive in my 4-drive RAID10 setup failed. What are my options? Drives are WD1000FYPS (Western Digital 1 TB 3.5" SATA). mdadm.conf: # mdadm.conf written out by anaconda MAILADDR root AUTO +imsm +1.x -all ARRAY /dev/md/root level=raid10 num-devices=4 UUID=942f512e:2db8dc6c:71667abc:daf408c3 /proc/mdstat: Personalities : [raid10] md127 : active raid10 sdf1[2](F)

...at we >> need. > I think you should start with simple approach and impove incrementally > if this turns out to be not optimal. I really detest taking struct pages > outside of the lock. You never know what might happen after the lock is > dropped. E.g. can you race with the memory hotremove? The caller won't use pages returned from the function, so I think there shouldn't be an issue or race if the returned pages are used (i.e. not free anymore) or simply gone due to hotremove. Best, Wei

--On Friday, September 18, 2020 10:53 PM +0200 Simon Matter <simon.matter at invoca.ch> wrote: > mdadm --remove /dev/md127 /dev/sdf1 > > and then the same with --add should hotremove and add dev device again. > > If it rebuilds fine it may again work for a long time. This worked like a charm. When I added it back, it told me it was "re-adding" the drive, so it recognized the drive I'd just removed. I checked /proc/mdstat and it showed rebuilding. It took...

...; I think you should start with simple approach and impove incrementally >>> if this turns out to be not optimal. I really detest taking struct pages >>> outside of the lock. You never know what might happen after the lock is >>> dropped. E.g. can you race with the memory hotremove? >> >> The caller won't use pages returned from the function, so I think there >> shouldn't be an issue or race if the returned pages are used (i.e. not free >> anymore) or simply gone due to hotremove. > No, this is just too error prone. Consider that struct page...

...rt with simple approach and impove incrementally >>>>> if this turns out to be not optimal. I really detest taking struct pages >>>>> outside of the lock. You never know what might happen after the lock is >>>>> dropped. E.g. can you race with the memory hotremove? >>>> The caller won't use pages returned from the function, so I think there >>>> shouldn't be an issue or race if the returned pages are used (i.e. not free >>>> anymore) or simply gone due to hotremove. >>> No, this is just too error prone. Co...

...le approach and impove incrementally > >>>>>if this turns out to be not optimal. I really detest taking struct pages > >>>>>outside of the lock. You never know what might happen after the lock is > >>>>>dropped. E.g. can you race with the memory hotremove? > >>>>The caller won't use pages returned from the function, so I think there > >>>>shouldn't be an issue or race if the returned pages are used (i.e. not free > >>>>anymore) or simply gone due to hotremove. > >>>No, this is just too...

...le approach and impove incrementally > >>>>>if this turns out to be not optimal. I really detest taking struct pages > >>>>>outside of the lock. You never know what might happen after the lock is > >>>>>dropped. E.g. can you race with the memory hotremove? > >>>>The caller won't use pages returned from the function, so I think there > >>>>shouldn't be an issue or race if the returned pages are used (i.e. not free > >>>>anymore) or simply gone due to hotremove. > >>>No, this is just too...

...other words as long as the driver knows the page has been returned to the host then it has ref count at 1. Once the page is returned to the guest for whatever reason it can free it to the system by clearing the offline state and put_page. An elevated ref count could help to detect that the memory hotremove is not safe until the driver removes all potential metadata it might still hold. You also know that memory online should skip such a page. All in all your page is still in use by the driver and the life cycle is controlled by that driver. Or am I am missing something? -- Michal Hocko SUSE Labs

...other words as long as the driver knows the page has been returned to the host then it has ref count at 1. Once the page is returned to the guest for whatever reason it can free it to the system by clearing the offline state and put_page. An elevated ref count could help to detect that the memory hotremove is not safe until the driver removes all potential metadata it might still hold. You also know that memory online should skip such a page. All in all your page is still in use by the driver and the life cycle is controlled by that driver. Or am I am missing something? -- Michal Hocko SUSE Labs

..._offline. (which is correct IMHO. As documented, PG_offline means "logically offline". The memmap is valid, however the page content should not be accessed. (PG_logically_offline would have been ugly ;) ). But that shouldn't be an issue right now. > admin might want to offline/hotremove the whole memory block via sysfs. The admin can only trigger offlining via sysfs. Hotremove is under control of the driver. (removing the whole memory block) And with the current virtio-mem prototype, this works like a charm. > An elevated reference count would prevent offlining to finish. A...

...ated reference count and have a more robust design as well. Let's say that you still keep a reference to your offlined pages and mark them offlined. That should make sure that no consumer of the pfn_to_online_page will touch the page's content nor the state. Now admin might want to offline/hotremove the whole memory block via sysfs. An elevated reference count would prevent offlining to finish. And I believe this is a good thing because the owner of the offline page might still need to do something to "untrack" that page. We have an interface for that - MEM_GOING_OFFLINE notification...

...ated reference count and have a more robust design as well. Let's say that you still keep a reference to your offlined pages and mark them offlined. That should make sure that no consumer of the pfn_to_online_page will touch the page's content nor the state. Now admin might want to offline/hotremove the whole memory block via sysfs. An elevated reference count would prevent offlining to finish. And I believe this is a good thing because the owner of the offline page might still need to do something to "untrack" that page. We have an interface for that - MEM_GOING_OFFLINE notification...

...'s got 6 bad blocks, 1 pending for remapping. > > Can I clear the error and rebuild? (It's not clear what commands would do > that.) Or should I buy a replacement drive? I'm considering a WDS100T1R0A Hi, mdadm --remove /dev/md127 /dev/sdf1 and then the same with --add should hotremove and add dev device again. If it rebuilds fine it may again work for a long time. Simon > (2.5" 1TB red drive), which Amazon has for $135, plus the 3.5" adapter. > > The system serves primarily as a home mail server (it fetchmails from an > outside VPS serving as my domain...

--On Friday, September 18, 2020 10:53 PM +0200 Simon Matter <simon.matter at invoca.ch> wrote: > mdadm --remove /dev/md127 /dev/sdf1 > > and then the same with --add should hotremove and add dev device again. > > If it rebuilds fine it may again work for a long time. Thanks. That reminds me: If I need to replace it, is there some easy way to figure out which drive bay is sdf? It's an old Supermicro rack chassis with 6 drive bays. Perhaps a way to blink the drive li...