Dne 27. 05. 22 v 14:20 Vivek Goyal napsal(a): > On Fri, May 27, 2022 at 02:45:14PM +0800, Tao Liu wrote: > > If lvm2 thinp is enabled in kdump, lvm2-monitor.service is needed for > > monitor and autoextend the size of thin pool. Otherwise the vmcore > > dumped to a no-enough-space target will be incomplete and unable for > > further analysis. > > > > In this patch, lvm2-monitor.service will be started before kdump-capture > > .service for 2nd kernel, then be stopped in kdump post.d phase. So > > the thin pool monitoring and size-autoextend can be ensured during kdump. > > > > Signed-off-by: Tao Liu <ltao(a)redhat.com&gt; > > --- > > dracut-lvm2-monitor.service | 15 +++++++++++++++ > > dracut-module-setup.sh | 16 ++++++++++++++++ > > kexec-tools.spec | 2 ++ > > 3 files changed, 33 insertions(+) > > create mode 100644 dracut-lvm2-monitor.service > > > > diff --git a/dracut-lvm2-monitor.service b/dracut-lvm2-monitor.service > This seems to be a copy of /lib/systemd/system/lvm2-monitor.service. > Wondering if we can dirctly include that file in initramfs when generating > image. But I am fuzzy on details of dracut implementation. It has been > too long since I played with it. So Bao and kdump team will be best > to comment on this. > This is quite interesting -  monitoring should in fact never be started wthin 'ramdisk'  so I'm acutlly wondering what is this service file doing there. Design was to start 'monitoring' of devices just after switch to 'rootfs' - since  running 'dmeventd' out of ramdisk does not make any sense at all.

(Adding also  Dave since he has been able to push some patches to 'dracut' recently') Regards Zdenek

Dne 27. 05. 22 v 16:50 Vivek Goyal napsal(a): > On Fri, May 27, 2022 at 04:42:25PM +0200, Zdenek Kabelac wrote: > > Dne 27. 05. 22 v 14:20 Vivek Goyal napsal(a): > > > On Fri, May 27, 2022 at 02:45:14PM +0800, Tao Liu wrote: > > > > If lvm2 thinp is enabled in kdump, lvm2-monitor.service is needed for > > > > monitor and autoextend the size of thin pool. Otherwise the vmcore > > > > dumped to a no-enough-space target will be incomplete and unable for > > > > further analysis. > > > > > > > > In this patch, lvm2-monitor.service will be started before kdump-capture > > > > .service for 2nd kernel, then be stopped in kdump post.d phase. So > > > > the thin pool monitoring and size-autoextend can be ensured during kdump. > > > > > > > > Signed-off-by: Tao Liu <ltao(a)redhat.com&gt; > > > > --- > > > > dracut-lvm2-monitor.service | 15 +++++++++++++++ > > > > dracut-module-setup.sh | 16 ++++++++++++++++ > > > > kexec-tools.spec | 2 ++ > > > > 3 files changed, 33 insertions(+) > > > > create mode 100644 dracut-lvm2-monitor.service > > > > > > > > diff --git a/dracut-lvm2-monitor.service b/dracut-lvm2-monitor.service > > > This seems to be a copy of /lib/systemd/system/lvm2-monitor.service. > > > Wondering if we can dirctly include that file in initramfs when generating > > > image. But I am fuzzy on details of dracut implementation. It has been > > > too long since I played with it. So Bao and kdump team will be best > > > to comment on this. > > > > > This is quite interesting -  monitoring should in fact never be started > > wthin 'ramdisk'  so I'm acutlly wondering what is this service file doing > > there. > > > > Design was to start 'monitoring' of devices just after switch to 'rootfs' - > > since  running 'dmeventd' out of ramdisk does not make any sense at all. > Hi Zdenek, > > In case of kdump, we save core dump from initramfs context and reboot > back into primary kernel. And that's why this need of dm monitoring ( > and thin pool auto extension) working from inside the initramfs > context. > So IMHO this although does not look like the best approach. AFAIK the lvm.conf within ramdisk is also a modified version. It looks like there should be a better alternative - like 'after' activation checking there is 'enough' room in thin-pool for use with  thinLV - should be 'computable' and in case the size is not good enough - try to extend  thin-pool prior use/mount of thinLV (size of space in thin-pool %DATA & %METATDATA and occupancy of %DATA thinLV could be obtained by  'lvs' tool)

Running very resource hungry  dmeventd (looks all the process memory in RAM - could be many  many MB) in  kdump environment is not IMHO worst option here  - I'd prefer to avoid execution of dmeventd in this ramfs image.

Dne 27. 05. 22 v 17:39 Vivek Goyal napsal(a): > On Fri, May 27, 2022 at 04:59:38PM +0200, Zdenek Kabelac wrote: > > Dne 27. 05. 22 v 16:50 Vivek Goyal napsal(a): > > > On Fri, May 27, 2022 at 04:42:25PM +0200, Zdenek Kabelac wrote: > > > > Dne 27. 05. 22 v 14:20 Vivek Goyal napsal(a): > > > > > On Fri, May 27, 2022 at 02:45:14PM +0800, Tao Liu wrote: > > > > > > If lvm2 thinp is enabled in kdump, lvm2-monitor.service is needed for > > > > > > monitor and autoextend the size of thin pool. Otherwise the vmcore > > > > > > dumped to a no-enough-space target will be incomplete and unable for > > > > > > further analysis. > > > > > > > > > > > > In this patch, lvm2-monitor.service will be started before kdump-capture > > > > > > .service for 2nd kernel, then be stopped in kdump post.d phase. So > > > > > > the thin pool monitoring and size-autoextend can be ensured during kdump. > > > > > > > > > > > > Signed-off-by: Tao Liu <ltao(a)redhat.com&gt; > > > > > > --- > > > > > > dracut-lvm2-monitor.service | 15 +++++++++++++++ > > > > > > dracut-module-setup.sh | 16 ++++++++++++++++ > > > > > > kexec-tools.spec | 2 ++ > > > > > > 3 files changed, 33 insertions(+) > > > > > > create mode 100644 dracut-lvm2-monitor.service > > > > > > > > > > > > diff --git a/dracut-lvm2-monitor.service b/dracut-lvm2-monitor.service > > > > > This seems to be a copy of /lib/systemd/system/lvm2-monitor.service. > > > > > Wondering if we can dirctly include that file in initramfs when generating > > > > > image. But I am fuzzy on details of dracut implementation. It has been > > > > > too long since I played with it. So Bao and kdump team will be best > > > > > to comment on this. > > > > > > > > > This is quite interesting -  monitoring should in fact never be started > > > > wthin 'ramdisk'  so I'm acutlly wondering what is this service file doing > > > > there. > > > > > > > > Design was to start 'monitoring' of devices just after switch to 'rootfs' - > > > > since  running 'dmeventd' out of ramdisk does not make any sense at all. > > > Hi Zdenek, > > > > > > In case of kdump, we save core dump from initramfs context and reboot > > > back into primary kernel. And that's why this need of dm monitoring ( > > > and thin pool auto extension) working from inside the initramfs > > > context. > > > > > So IMHO this although does not look like the best approach. AFAIK the > > lvm.conf within ramdisk is also a modified version. > > > > It looks like there should be a better alternative - like 'after' activation > > checking there is 'enough' room in thin-pool for use with  thinLV - should > > be 'computable' and in case the size is not good enough - try to extend > > thin-pool prior use/mount of thinLV (size of space in thin-pool %DATA & > > %METATDATA and occupancy of %DATA thinLV could be obtained by  'lvs' tool) > One potential problem here is that we don't know what's the size of > vmcore in advance. It gets filtered and saved and we dont know in > advance, how many kernel pages will be there. > > Is that still right, Bao? > > Technically speaking, one could first run makedumpfile to just determine > what will be size of vmcore and then actually save vmcore in second > round. But that will double the filtering time. You could likely 'stream/buffer'  these  kdump data in form of i.e. '4MiB ~ 128MiB' chunks (or any other suitable size which will be 'quick enough) and before each new write of such chunk just compare there is enough free space in thin-pool with lvs -  should be still better then running 'dmeventd' in the background  -

and gives you also the best control over  the  deadlock in case you run completely out-of-space (i.e. leaving enough room in thin-pool and avoiding  full dump  so user could still 'boot')

Since you will be only a single user of thinLV in initramfs - this should be reasonable straigforward to achieve. Regards Zdenek

On Fri, May 27, 2022 at 01:05:57PM -0400, Vivek Goyal wrote: > So if we fill up thin pool completely, it might fail to activate over > reboot? I do remember there were issues w.r.t filling up thin pool > compltely and it was not desired. > > So above does not involve growing thin pool at all? Above just says, > query currently available space in thin pool and when it is about > to be full, stop writing to it? This is suboptimal if there is > free space in underlying volume group. > > Ok, this is going to be ugly given how kdump works right now. We have > this config option core_collector where user can specify how vmcore > should be saved (dd, cp, makedumpfile, .....) > > None of these tools know about streaming and thin pool extension etc. > > I guess one could think of making maekdumpfile aware of thin pool. But > given there can be so many dump targets, it will be really ugly from > design point of view. Embedding knowledge of a target in a generic > filtering tool. > > Alternatively we could probably write a tool of our own and pipe > makedumpfile output to it. But then user will have to specify it > in core_collector for thin pool targets only. > > None of the solutions look clean or fit well into the current design. Maybe I'm not following, but all this sounds unnecessarily complicated. Roughly estimate largest possible kdump size (X MB). Check that the thin pool has X MB free. If not, lvextend -L+XMB the thin pool. If lvextend doesn't find X MB in the vg, then quit without kdump.

Dne 27. 05. 22 v 19:26 Vivek Goyal napsal(a): > On Fri, May 27, 2022 at 12:16:38PM -0500, David Teigland wrote: >> On Fri, May 27, 2022 at 01:05:57PM -0400, Vivek Goyal wrote: >>> So if we fill up thin pool completely, it might fail to activate over >>> reboot? I do remember there were issues w.r.t filling up thin pool >>> compltely and it was not desired. >>> >>> So above does not involve growing thin pool at all? Above just says, >>> query currently available space in thin pool and when it is about >>> to be full, stop writing to it? This is suboptimal if there is >>> free space in underlying volume group. >>> >>> Ok, this is going to be ugly given how kdump works right now. We have >>> this config option core_collector where user can specify how vmcore >>> should be saved (dd, cp, makedumpfile, .....) >>> >>> None of these tools know about streaming and thin pool extension etc. >>> >>> I guess one could think of making maekdumpfile aware of thin pool. But >>> given there can be so many dump targets, it will be really ugly from >>> design point of view. Embedding knowledge of a target in a generic >>> filtering tool. >>> >>> Alternatively we could probably write a tool of our own and pipe >>> makedumpfile output to it. But then user will have to specify it >>> in core_collector for thin pool targets only. >>> >>> None of the solutions look clean or fit well into the current design. >> Maybe I'm not following, but all this sounds unnecessarily complicated. >> Roughly estimate largest possible kdump size (X MB). >> Check that the thin pool has X MB free. >> If not, lvextend -L+XMB the thin pool. >> If lvextend doesn't find X MB in the vg, then quit without kdump. > Estimation is hard. We could just look at raw (unfiltered /proc/vmcore > size) and extend it. But problem there is we also support kdump > on multi terabyte machines. And after filtering final vmcore could > be just few GB. So extending thin pool to say 12TB might very well > fail and we fail to save dump. > > May be use above trick for dd and cp core_collectors as they will not > filter anything. > > And for makedumpfile, run it twice. First run only gives size estimate > and second run actually saves the dump. And do this only for thin volumes > targets. This will almost double dump saving time. > > So ideally it will be nice if we can enable automatic thin pool extension > from initramfs. For kdump environment - this is certainly not ideal - is this itself requires lot of RAM - buffered processing should be doable even in plain bash - if you can pipe 'dd' to it. As mentioned previously - it would be also good to make sure thin-pool leaves some 'configured' free space  - so  i.e. those multiTIB do not overfill thin-pool and make possibly system hard to use after such captured  kdump   (although one could imagine) just  to  'drop'  kdump  if thin-pool runs over some threshold) to keep things simple. (So i.e. if  kdump fills thinpool   over >99%  - drop it - so use could use thin-pool after reboot -  better to have usable system in this case I'd say)

On Fri, May 27, 2022 at 04:59:38PM +0200, Zdenek Kabelac wrote: > Dne 27. 05. 22 v 16:50 Vivek Goyal napsal(a): > > On Fri, May 27, 2022 at 04:42:25PM +0200, Zdenek Kabelac wrote: > > > Dne 27. 05. 22 v 14:20 Vivek Goyal napsal(a): > > > > On Fri, May 27, 2022 at 02:45:14PM +0800, Tao Liu wrote: > > > > > If lvm2 thinp is enabled in kdump, lvm2-monitor.service is needed for > > > > > monitor and autoextend the size of thin pool. Otherwise the vmcore > > > > > dumped to a no-enough-space target will be incomplete and unable for > > > > > further analysis. > > > > > > > > > > In this patch, lvm2-monitor.service will be started before kdump-capture > > > > > .service for 2nd kernel, then be stopped in kdump post.d phase. So > > > > > the thin pool monitoring and size-autoextend can be ensured during kdump. > > > > > > > > > > Signed-off-by: Tao Liu <ltao(a)redhat.com&gt; > > > > > --- > > > > > dracut-lvm2-monitor.service | 15 +++++++++++++++ > > > > > dracut-module-setup.sh | 16 ++++++++++++++++ > > > > > kexec-tools.spec | 2 ++ > > > > > 3 files changed, 33 insertions(+) > > > > > create mode 100644 dracut-lvm2-monitor.service > > > > > > > > > > diff --git a/dracut-lvm2-monitor.service b/dracut-lvm2-monitor.service > > > > This seems to be a copy of /lib/systemd/system/lvm2-monitor.service. > > > > Wondering if we can dirctly include that file in initramfs when generating > > > > image. But I am fuzzy on details of dracut implementation. It has been > > > > too long since I played with it. So Bao and kdump team will be best > > > > to comment on this. > > > > > > > This is quite interesting -  monitoring should in fact never be started > > > wthin 'ramdisk'  so I'm acutlly wondering what is this service file doing > > > there. > > > > > > Design was to start 'monitoring' of devices just after switch to 'rootfs' - > > > since  running 'dmeventd' out of ramdisk does not make any sense at all. > > Hi Zdenek, > > > > In case of kdump, we save core dump from initramfs context and reboot > > back into primary kernel. And that's why this need of dm monitoring ( > > and thin pool auto extension) working from inside the initramfs > > context. > > > > So IMHO this although does not look like the best approach. AFAIK the > lvm.conf within ramdisk is also a modified version. > > It looks like there should be a better alternative - like 'after' activation > checking there is 'enough' room in thin-pool for use with  thinLV - should > be 'computable' and in case the size is not good enough - try to extend  > thin-pool prior use/mount of thinLV (size of space in thin-pool %DATA & > %METATDATA and occupancy of %DATA thinLV could be obtained by  'lvs' tool) One potential problem here is that we don't know what's the size of vmcore in advance. It gets filtered and saved and we dont know in advance, how many kernel pages will be there. Is that still right, Bao?

Technically speaking, one could first run makedumpfile to just determine what will be size of vmcore and then actually save vmcore in second round. But that will double the filtering time.

> > Running very resource hungry  dmeventd (looks all the process memory in RAM > - could be many  many MB) in  kdump environment is not IMHO worst option > here  - I'd prefer to avoid execution of dmeventd in this ramfs image. I understand. We also want to keep the size of kdump initramfs to the minimum.

Dne 30. 05. 22 v 4:34 Baoquan He napsal(a): > On 05/27/22 at 11:39am, Vivek Goyal wrote: > > On Fri, May 27, 2022 at 04:59:38PM +0200, Zdenek Kabelac wrote: > > > Dne 27. 05. 22 v 16:50 Vivek Goyal napsal(a): > > > > On Fri, May 27, 2022 at 04:42:25PM +0200, Zdenek Kabelac wrote: > > > > > Dne 27. 05. 22 v 14:20 Vivek Goyal napsal(a): > > > > > > On Fri, May 27, 2022 at 02:45:14PM +0800, Tao Liu wrote: > > > > > > > If lvm2 thinp is enabled in kdump, lvm2-monitor.service is needed for > > > > > > > monitor and autoextend the size of thin pool. Otherwise the vmcore > > > > > > > dumped to a no-enough-space target will be incomplete and unable for > > > > > > > further analysis. > > > > > > > > > > > > > > In this patch, lvm2-monitor.service will be started before kdump-capture > > > > > > > .service for 2nd kernel, then be stopped in kdump post.d phase. So > > > > > > > the thin pool monitoring and size-autoextend can be ensured during kdump. > > > > > > > > > > > > > > Signed-off-by: Tao Liu <ltao(a)redhat.com&gt; > > > > > > > --- > > > > > > > dracut-lvm2-monitor.service | 15 +++++++++++++++ > > > > > > > dracut-module-setup.sh | 16 ++++++++++++++++ > > > > > > > kexec-tools.spec | 2 ++ > > > > > > > 3 files changed, 33 insertions(+) > > > > > > > create mode 100644 dracut-lvm2-monitor.service > > > > > > > > > > > > > > diff --git a/dracut-lvm2-monitor.service b/dracut-lvm2-monitor.service > > > > > > This seems to be a copy of /lib/systemd/system/lvm2-monitor.service. > > > > > > Wondering if we can dirctly include that file in initramfs when generating > > > > > > image. But I am fuzzy on details of dracut implementation. It has been > > > > > > too long since I played with it. So Bao and kdump team will be best > > > > > > to comment on this. > > > > > > > > > > > This is quite interesting -  monitoring should in fact never be started > > > > > wthin 'ramdisk'  so I'm acutlly wondering what is this service file doing > > > > > there. > > > > > > > > > > Design was to start 'monitoring' of devices just after switch to 'rootfs' - > > > > > since  running 'dmeventd' out of ramdisk does not make any sense at all. > > > > Hi Zdenek, > > > > > > > > In case of kdump, we save core dump from initramfs context and reboot > > > > back into primary kernel. And that's why this need of dm monitoring ( > > > > and thin pool auto extension) working from inside the initramfs > > > > context. > > > > > > > So IMHO this although does not look like the best approach. AFAIK the > > > lvm.conf within ramdisk is also a modified version. > > > > > > It looks like there should be a better alternative - like 'after' activation > > > checking there is 'enough' room in thin-pool for use with  thinLV - should > > > be 'computable' and in case the size is not good enough - try to extend > > > thin-pool prior use/mount of thinLV (size of space in thin-pool %DATA & > > > %METATDATA and occupancy of %DATA thinLV could be obtained by  'lvs' tool) > > One potential problem here is that we don't know what's the size of > > vmcore in advance. It gets filtered and saved and we dont know in > > advance, how many kernel pages will be there. > > > > Is that still right, Bao? > Yes, it's still right. > > We have features in makedumpfile to estimate the expected disk space for > vmcore dumping. E.g System RAM is 2TB, makedumpfile running tells 256GB > disk space is needed for storing vmcore, by filtering out zero pages, > unused pages, etc. However, that estimation is done in 1st kernel, and > the running kernel could dynamically allocate pages. So the estimation > can only give very rough data, in magnitude level. E.g you have 1TB > memory, while the disk space is only 200GB, that's obviously not enough. > > > Technically speaking, one could first run makedumpfile to just determine > > what will be size of vmcore and then actually save vmcore in second > > round. But that will double the filtering time. > Yeah. Besides, memory content of system is changing dynamically all the > time. E.g your oracle DB is running or not running, the user space data > is defintely not the same. And two times of work need involve people's > manual work, automation is still expected if can be made. > > > > Running very resource hungry  dmeventd (looks all the process memory in RAM > > > - could be many  many MB) in  kdump environment is not IMHO worst option > > > here  - I'd prefer to avoid execution of dmeventd in this ramfs image. > > I understand. We also want to keep the size of kdump initramfs to the > > minimum. > Right. > > I talked to Tao, he tested on kvm guest with 500M memory and 100M disk > space to trigger the insufficient disk space usage. Tao said the > dmeventd will cosume about 40MB when executing. I am not familiar with > dmeventd, if its running will cost about constant 40M memory, no matter > how much disk space need be extended at one time, we can adjust our > kdump script to increase the default crashkernel= value if lvm2 thinp is > detected. It looks acceptable in kdump side. Dmeventd runs  in 'mlockall()'  mode - so the whole executable with all libraries and all the memory allocations are pinned in RAM  (so IMHO 40MiB is way small number) Reason for this is - in the normal 'running' mode lvm2 protects dmeventd from being blocked when it would run out of rootfs and it would suspend DM with rootfs on it - so by having the whole binary mlocked  in RAM it cannot cause 'deadlock' waiting on itsefl when it suspends given DM device. For kdump executional environment in  ramdisk this is not really relevant condition (but dmeventd was not designed to be executed in such environment).  However as mentioned in my previous post - it's actually more useful to run  'lvm lvextend --use-policies' with given thin-pool name  in  a plain shell parallel loop -  as it  basically gives  same result with way less  memory 'obstruction'  and with far better control as well (i.e.  leaving user a defined minimum to be sure it can actuall boot afterwards -  so dumping only when there really is some space...)

Regards Zdenek

On Fri, May 27, 2022 at 02:45:12PM +0800, Tao Liu wrote: > Thin provision is a mechanism that you can allocate a lvm volume which has > a large virtual size for file systems but actually in a small physical > size. The physical size can be autoextended in use if thin pool reached a > threshold specified in /etc/lvm/lvm.conf. So what's the core requirement? Is it about that root filesystem of the machine is on a thin device and after crash we are trying to save dump to rootfs. Typically rootfs might have been setup for auto-extension. But problem here is that you are dumping the core from initrafsm context and auto extension might not work out of the box? So you are basically trying to pack dmeventd systemd unit file into initramfs and /etc/lvm/lvm.conf in initramfs to make auto extension work.

Vivek > > There are 2 works should be handled when enable lvm2 thinp for kdump: > > 1) Check if the dump target device or directory is thinp device. > 2) Monitor the thin pool and autoextend its size when it reached the threshold > during kdump. > > According to my testing, the memory consumption procedure for lvm2 thinp is the thin pool > size-autoextend phase. For fedora and rhel9, the default crashkernel value is enough. But > for rhel8, the default crashkernel value 1G-4G:160M is not enough, so it should > be handled particularly. > > v1 -> v2: > > 1) Modified the usage of lvs cmd when check if target is lvm2 thinp > device. > 2) Removed the sync flag way of mounting for lvm2 thinp target > during kdump, use "sync -f vmcore" to force sync data, and handle > the error if fails. > > v2 -> v3: > > 1) Removed "sync -f vmcore" patch out of the patch set, for it is > addressing an issue which is not specifically to lvm2 thinp support for > kdump. > > Tao Liu (3): > Add lvm2 thin provision dump target checker > Add lvm2-monitor.service for kdump when lvm2 thinp enabled > lvm.conf should be check modified if lvm2 thinp enabled > > dracut-lvm2-monitor.service | 15 +++++++++++++++ > dracut-module-setup.sh | 16 ++++++++++++++++ > kdump-lib-initramfs.sh | 20 ++++++++++++++++++++ > kdumpctl | 1 + > kexec-tools.spec | 2 ++ > 5 files changed, 54 insertions(+) > create mode 100644 dracut-lvm2-monitor.service > > -- > 2.33.1 >

Hi Tao, On Mon, 30 May 2022 at 11:31, Tao Liu <ltao(a)redhat.com&gt; wrote: > > Hi Vivek, > > On Fri, May 27, 2022 at 8:56 PM Vivek Goyal <vgoyal(a)redhat.com&gt; wrote: > > > > On Fri, May 27, 2022 at 02:45:12PM +0800, Tao Liu wrote: > > > Thin provision is a mechanism that you can allocate a lvm volume which has > > > a large virtual size for file systems but actually in a small physical > > > size. The physical size can be autoextended in use if thin pool reached a > > > threshold specified in /etc/lvm/lvm.conf. > > > > So what's the core requirement? Is it about that root filesystem of > > the machine is on a thin device and after crash we are trying to save > > dump to rootfs. > > > > Typically rootfs might have been setup for auto-extension. But problem > > here is that you are dumping the core from initrafsm context and > > auto extension might not work out of the box? So you are basically > > trying to pack dmeventd systemd unit file into initramfs and > > /etc/lvm/lvm.conf in initramfs to make auto extension work. > > > > This patch set enables the feature that kdump to a lvm2 thinp volume. > If the target is thinp volume, then the case of thinp pool > autoextension should be considered. For thinp volume, it reports to > have 1G space for its file system within, but it only allocated 100M > physical space from thinp pool for example. As data is written in, > more physical space is needed by thinp volume, thus thinp pool must be > able to autoextend to provide more physical space to thinp volume. The > autoextend threshold is defined in lvm.conf, and it is achieved by a > monitor service defined in a dmeventd systemd unit file. > > So lvm.conf and the systemd unit file should be packed into the > initramfs image, for the use of lvm thinp during kdump. The > requirement above is generic, it doesn't matter if the rootfs we are > dumping to is on a thinp volume. I think Vivek means about we should follow how dracut handle lvm in initramfs, Vivek, please correct me if this is not you want. This patchset enable lvm thin in initramfs, I think the right place to handle this is the 90lvm dracut module or to add another 91lvmthin dracut module. And in dracut initramfs code, it just parse the kernel cmdline to setup lvm instead of adding the lvm config files, the lvm thin support could be done in similar way.

> > Thanks, > Tao Liu > > > Vivek > > > > > > There are 2 works should be handled when enable lvm2 thinp for kdump: > > > > > > 1) Check if the dump target device or directory is thinp device. > > > 2) Monitor the thin pool and autoextend its size when it reached the threshold > > > during kdump. > > > > > > According to my testing, the memory consumption procedure for lvm2 thinp is the thin pool > > > size-autoextend phase. For fedora and rhel9, the default crashkernel value is enough. But > > > for rhel8, the default crashkernel value 1G-4G:160M is not enough, so it should > > > be handled particularly. > > > > > > v1 -> v2: > > > > > > 1) Modified the usage of lvs cmd when check if target is lvm2 thinp > > > device. > > > 2) Removed the sync flag way of mounting for lvm2 thinp target > > > during kdump, use "sync -f vmcore" to force sync data, and handle > > > the error if fails. > > > > > > v2 -> v3: > > > > > > 1) Removed "sync -f vmcore" patch out of the patch set, for it is > > > addressing an issue which is not specifically to lvm2 thinp support for > > > kdump. > > > > > > Tao Liu (3): > > > Add lvm2 thin provision dump target checker > > > Add lvm2-monitor.service for kdump when lvm2 thinp enabled > > > lvm.conf should be check modified if lvm2 thinp enabled > > > > > > dracut-lvm2-monitor.service | 15 +++++++++++++++ > > > dracut-module-setup.sh | 16 ++++++++++++++++ > > > kdump-lib-initramfs.sh | 20 ++++++++++++++++++++ > > > kdumpctl | 1 + > > > kexec-tools.spec | 2 ++ > > > 5 files changed, 54 insertions(+) > > > create mode 100644 dracut-lvm2-monitor.service > > > > > > -- > > > 2.33.1 > > > > > >