From: Paolo Bonzini <pbonzini@redhat.com>
To: Igor Mammedov <imammedo@redhat.com>, qemu-devel@nongnu.org
Cc: mst@redhat.com
Subject: Re: [Qemu-devel] [RFC v2 3/6] memory: support unmapping of MemoryRegion mapped into HVA parent
Date: Mon, 08 Jun 2015 17:32:27 +0200 [thread overview]
Message-ID: <5575B58B.50105@redhat.com> (raw)
In-Reply-To: <1433776757-61958-4-git-send-email-imammedo@redhat.com>
On 08/06/2015 17:19, Igor Mammedov wrote:
> +void qemu_ram_unmap_hva(ram_addr_t addr)
> +{
> + RAMBlock *block = find_ram_block(addr);
> +
> + assert(block);
> + mmap(block->host, block->used_length, PROT_NONE,
> + MAP_FIXED | MAP_NORESERVE | MAP_ANONYMOUS | MAP_PRIVATE, -1, 0);
> +}
> +
Hmm, this is not good. :( The area at block->host can be in use, for
example via memory_region_ref/memory_region_unref. This can happen a
bit after the memory_region_del_subregion. So you can SEGV if you
simply make a synchronous update. I'm not sure if there is a solution
(but thanks for splitting the patches in a way that made the problem
clear!).
Paolo
next prev parent reply other threads:[~2015-06-08 15:32 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-06-08 15:19 [Qemu-devel] [RFC v2 0/6] Fix QEMU crash during memory hotplug with vhost=on Igor Mammedov
2015-06-08 15:19 ` [Qemu-devel] [RFC v2 1/6] memory: get rid of memory_region_destructor_ram_from_ptr() Igor Mammedov
2015-06-08 15:23 ` Paolo Bonzini
2015-06-08 16:08 ` Igor Mammedov
2015-06-08 16:09 ` Paolo Bonzini
2015-06-08 16:26 ` Igor Mammedov
2015-06-08 15:19 ` [Qemu-devel] [RFC v2 2/6] memory: introduce MemoryRegion container with reserved HVA range Igor Mammedov
2015-06-08 15:19 ` [Qemu-devel] [RFC v2 3/6] memory: support unmapping of MemoryRegion mapped into HVA parent Igor Mammedov
2015-06-08 15:26 ` Paolo Bonzini
2015-06-08 15:32 ` Paolo Bonzini [this message]
2015-06-08 16:13 ` Igor Mammedov
2015-06-08 16:25 ` Michael S. Tsirkin
2015-06-08 17:06 ` Paolo Bonzini
2015-06-09 10:08 ` Igor Mammedov
2015-06-17 8:14 ` Paolo Bonzini
2015-06-17 15:04 ` Igor Mammedov
2015-06-17 15:10 ` Michael S. Tsirkin
2015-06-17 16:15 ` Paolo Bonzini
2015-06-17 16:30 ` Michael S. Tsirkin
2015-06-08 15:19 ` [Qemu-devel] [RFC v2 4/6] hostmem: return recreated MemoryRegion if current can't be reused Igor Mammedov
2015-06-08 15:30 ` Paolo Bonzini
2015-06-08 16:25 ` Igor Mammedov
2015-06-08 16:28 ` Paolo Bonzini
2015-06-08 15:19 ` [Qemu-devel] [RFC v2 5/6] pc: reserve hotpluggable memory range with memory_region_init_hva_range() Igor Mammedov
2015-06-08 15:19 ` [Qemu-devel] [RFC v2 6/6] pc: fix QEMU crashing when more than ~50 memory hotplugged Igor Mammedov
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