From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 65E15188CA9 for ; Fri, 15 Nov 2024 08:46:42 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=170.10.129.124 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1731660404; cv=none; b=JHTeZ23xM8RLok0ytBkVckIaxrHdcUcMVqqXtrEJIGiGs4HuerBBnn3gG71ljjBYjHKeLSIF3tZXSguDiC4bBLE0sSVUMqKiZTIIU0iI1ih7NBJw/ZzRU/C0AI6qLPXoRJvJV5C905YgAgT2m1s+ro1cECbYOR5eZaGDTS4N0EM= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1731660404; c=relaxed/simple; bh=Y+MsEKnzmc/83yMVSNfuCtSeI6/WxsCKwrXXNhZ5XLg=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=Zj/NNDZob9h3tsYGoqyu2u3m+dOYLbUOEGzJ5k26t5Typh39mhi9gvveGCHlQcIoo2VaMd0TimzKKhVdsjOeXbJG+B+CgnlX47pKLCQBWdFvD7mYArQlPhRwS2vx4idc/vL/FssOgML+z4d397zQ7eII4rZqx+XfkA4F09gFaYc= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=redhat.com; spf=pass smtp.mailfrom=redhat.com; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b=DNvcV98o; arc=none smtp.client-ip=170.10.129.124 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=redhat.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=redhat.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="DNvcV98o" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1731660401; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=iU3AwiO23RxdWGWn7Yp7jp33a5YtE5yN//tDV9uC5Ss=; b=DNvcV98o95278eYdFS1fxbZWTBdd+ftk0xI+ACyvgbNcnHigC5VNIp/BQj+DbiSpjs97pZ RBw+hdC9CWy/jjyjbZUHjnzAReCYclgkEARqjWH8fR9ECuwgO/Ed1xjfOauoNW/fA47oGh P/76ZS8viMMPgjyUTGpfIZ7KWfDFmMw= Received: from mx-prod-mc-05.mail-002.prod.us-west-2.aws.redhat.com (ec2-54-186-198-63.us-west-2.compute.amazonaws.com [54.186.198.63]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-119-Ae3uHm1KMM642lvste8crA-1; Fri, 15 Nov 2024 03:46:37 -0500 X-MC-Unique: Ae3uHm1KMM642lvste8crA-1 X-Mimecast-MFC-AGG-ID: Ae3uHm1KMM642lvste8crA Received: from mx-prod-int-04.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-04.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.40]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mx-prod-mc-05.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 0C2E31955F41; Fri, 15 Nov 2024 08:46:35 +0000 (UTC) Received: from localhost (unknown [10.72.113.10]) by mx-prod-int-04.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id A99EE1956054; Fri, 15 Nov 2024 08:46:32 +0000 (UTC) Date: Fri, 15 Nov 2024 16:46:27 +0800 From: Baoquan He To: David Hildenbrand Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org, linux-s390@vger.kernel.org, virtualization@lists.linux.dev, kvm@vger.kernel.org, linux-fsdevel@vger.kernel.org, kexec@lists.infradead.org, Heiko Carstens , Vasily Gorbik , Alexander Gordeev , Christian Borntraeger , Sven Schnelle , "Michael S. Tsirkin" , Jason Wang , Xuan Zhuo , Eugenio =?iso-8859-1?Q?P=E9rez?= , Vivek Goyal , Dave Young , Thomas Huth , Cornelia Huck , Janosch Frank , Claudio Imbrenda , Eric Farman , Andrew Morton Subject: Re: [PATCH v1 00/11] fs/proc/vmcore: kdump support for virtio-mem on s390 Message-ID: References: <20241025151134.1275575-1-david@redhat.com> Precedence: bulk X-Mailing-List: virtualization@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20241025151134.1275575-1-david@redhat.com> X-Scanned-By: MIMEDefang 3.0 on 10.30.177.40 On 10/25/24 at 05:11pm, David Hildenbrand wrote: > This is based on "[PATCH v3 0/7] virtio-mem: s390 support" [1], which adds > virtio-mem support on s390. > > The only "different than everything else" thing about virtio-mem on s390 > is kdump: The crash (2nd) kernel allocates+prepares the elfcore hdr > during fs_init()->vmcore_init()->elfcorehdr_alloc(). Consequently, the > crash kernel must detect memory ranges of the crashed/panicked kernel to > include via PT_LOAD in the vmcore. > > On other architectures, all RAM regions (boot + hotplugged) can easily be > observed on the old (to crash) kernel (e.g., using /proc/iomem) to create > the elfcore hdr. > > On s390, information about "ordinary" memory (heh, "storage") can be > obtained by querying the hypervisor/ultravisor via SCLP/diag260, and > that information is stored early during boot in the "physmem" memblock > data structure. > > But virtio-mem memory is always detected by as device driver, which is > usually build as a module. So in the crash kernel, this memory can only be ~~~~~~~~~~~ Is it 1st kernel or 2nd kernel? Usually we call the 1st kernel as panicked kernel, crashed kernel, the 2nd kernel as kdump kernel. > properly detected once the virtio-mem driver started up. > > The virtio-mem driver already supports the "kdump mode", where it won't > hotplug any memory but instead queries the device to implement the > pfn_is_ram() callback, to avoid reading unplugged memory holes when reading > the vmcore. > > With this series, if the virtio-mem driver is included in the kdump > initrd -- which dracut already takes care of under Fedora/RHEL -- it will > now detect the device RAM ranges on s390 once it probes the devices, to add > them to the vmcore using the same callback mechanism we already have for > pfn_is_ram(). Do you mean on s390 virtio-mem memory region will be detected and added to vmcore in kdump kernel when virtio-mem driver is initialized? Not sure if I understand it correctly. > > To add these device RAM ranges to the vmcore ("patch the vmcore"), we will > add new PT_LOAD entries that describe these memory ranges, and update > all offsets vmcore size so it is all consistent. > > Note that makedumfile is shaky with v6.12-rcX, I made the "obvious" things > (e.g., free page detection) work again while testing as documented in [2]. > > Creating the dumps using makedumpfile seems to work fine, and the > dump regions (PT_LOAD) are as expected. I yet have to check in more detail > if the created dumps are good (IOW, the right memory was dumped, but it > looks like makedumpfile reads the right memory when interpreting the > kernel data structures, which is promising). > > Patch #1 -- #6 are vmcore preparations and cleanups > Patch #7 adds the infrastructure for drivers to report device RAM > Patch #8 + #9 are virtio-mem preparations > Patch #10 implements virtio-mem support to report device RAM > Patch #11 activates it for s390, implementing a new function to fill > PT_LOAD entry for device RAM > > [1] https://lkml.kernel.org/r/20241025141453.1210600-1-david@redhat.com > [2] https://github.com/makedumpfile/makedumpfile/issues/16 > > Cc: Heiko Carstens > Cc: Vasily Gorbik > Cc: Alexander Gordeev > Cc: Christian Borntraeger > Cc: Sven Schnelle > Cc: "Michael S. Tsirkin" > Cc: Jason Wang > Cc: Xuan Zhuo > Cc: "Eugenio Pérez" > Cc: Baoquan He > Cc: Vivek Goyal > Cc: Dave Young > Cc: Thomas Huth > Cc: Cornelia Huck > Cc: Janosch Frank > Cc: Claudio Imbrenda > Cc: Eric Farman > Cc: Andrew Morton > > David Hildenbrand (11): > fs/proc/vmcore: convert vmcore_cb_lock into vmcore_mutex > fs/proc/vmcore: replace vmcoredd_mutex by vmcore_mutex > fs/proc/vmcore: disallow vmcore modifications after the vmcore was > opened > fs/proc/vmcore: move vmcore definitions from kcore.h to crash_dump.h > fs/proc/vmcore: factor out allocating a vmcore memory node > fs/proc/vmcore: factor out freeing a list of vmcore ranges > fs/proc/vmcore: introduce PROC_VMCORE_DEVICE_RAM to detect device RAM > ranges in 2nd kernel > virtio-mem: mark device ready before registering callbacks in kdump > mode > virtio-mem: remember usable region size > virtio-mem: support CONFIG_PROC_VMCORE_DEVICE_RAM > s390/kdump: virtio-mem kdump support (CONFIG_PROC_VMCORE_DEVICE_RAM) > > arch/s390/Kconfig | 1 + > arch/s390/kernel/crash_dump.c | 39 +++-- > drivers/virtio/Kconfig | 1 + > drivers/virtio/virtio_mem.c | 103 +++++++++++++- > fs/proc/Kconfig | 25 ++++ > fs/proc/vmcore.c | 258 +++++++++++++++++++++++++--------- > include/linux/crash_dump.h | 47 +++++++ > include/linux/kcore.h | 13 -- > 8 files changed, 396 insertions(+), 91 deletions(-) > > -- > 2.46.1 >