| Message ID | 20250109-san-v7-1-93c432a73024@daynix.com (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | Fix check-qtest-ppc64 sanitizer errors | expand |
On Thu, 9 Jan 2025, Akihiko Odaki wrote: > Do not refer to "memory region's reference count" > ------------------------------------------------- > > Now MemoryRegions do have their own reference counts, but they will not > be used when their owners are not themselves. However, the documentation > of memory_region_ref() says it adds "1 to a memory region's reference > count", which is confusing. Avoid referring to "memory region's > reference count" and just say: "Add a reference to a memory region". > Make a similar change to memory_region_unref() too. > > Refer to docs/devel/memory.rst for "owner" > ------------------------------------------ > > memory_region_ref() and memory_region_unref() used to have their own > descriptions of "owner", but they are somewhat out-of-date and > misleading. > > In particular, they say "whenever memory regions are accessed outside > the BQL, they need to be preserved against hot-unplug", but protecting > against hot-unplug is not mandatory if it is known that they will never > be hot-unplugged. They also say "MemoryRegions actually do not have > their own reference count", but they actually do. They just will not be > used unless their owners are not themselves. > > Refer to docs/devel/memory.rst as the single source of truth instead of > maintaining duplicate descriptions of "owner". > > Clarify that owner may be missing > > --------------------------------- > A memory region may not have an owner, and memory_region_ref() and > memory_region_unref() do nothing for such. > > memory: Clarify owner must not call memory_region_ref() > -------------------------------------------------------- > > The owner must not call this function as it results in a circular > reference. > > Signed-off-by: Akihiko Odaki <akihiko.odaki@daynix.com> > Reviewed-by: Peter Xu <peterx@redhat.com> > --- > include/exec/memory.h | 59 ++++++++++++++++++++++++--------------------------- > 1 file changed, 28 insertions(+), 31 deletions(-) > > diff --git a/include/exec/memory.h b/include/exec/memory.h > index 9458e2801d50..ca247343f433 100644 > --- a/include/exec/memory.h > +++ b/include/exec/memory.h > @@ -1210,7 +1210,7 @@ void memory_region_section_free_copy(MemoryRegionSection *s); > * memory_region_add_subregion() to add subregions. > * > * @mr: the #MemoryRegion to be initialized > - * @owner: the object that tracks the region's reference count > + * @owner: the object that keeps the region alive > * @name: used for debugging; not visible to the user or ABI > * @size: size of the region; any subregions beyond this size will be clipped > */ > @@ -1220,29 +1220,26 @@ void memory_region_init(MemoryRegion *mr, > uint64_t size); > > /** > - * memory_region_ref: Add 1 to a memory region's reference count > + * memory_region_ref: Add a reference to the owner of a memory region > * > - * Whenever memory regions are accessed outside the BQL, they need to be > - * preserved against hot-unplug. MemoryRegions actually do not have their > - * own reference count; they piggyback on a QOM object, their "owner". > - * This function adds a reference to the owner. > - * > - * All MemoryRegions must have an owner if they can disappear, even if the > - * device they belong to operates exclusively under the BQL. This is because > - * the region could be returned at any time by memory_region_find, and this > - * is usually under guest control. > + * This function adds a reference to the owner of a memory region to keep the > + * memory region alive. It does nothing if the owner is not present as a memory > + * region without owner will never die. > + * For references internal to the owner, use object_ref() instead to avoid a > + * circular reference. Reading this again I'm still confused by this last sentence. Do you mean references internal to the memory region should use object_ref on the memory region or that other references to the owner should use object_ref on the owner? This sentence is still not clear about that. Regards, BALATON Zoltan > + * See docs/devel/memory.rst to know about owner. > * > * @mr: the #MemoryRegion > */ > void memory_region_ref(MemoryRegion *mr); > > /** > - * memory_region_unref: Remove 1 to a memory region's reference count > + * memory_region_unref: Remove a reference to the memory region of the owner > * > - * Whenever memory regions are accessed outside the BQL, they need to be > - * preserved against hot-unplug. MemoryRegions actually do not have their > - * own reference count; they piggyback on a QOM object, their "owner". > - * This function removes a reference to the owner and possibly destroys it. > + * This function removes a reference to the owner of a memory region and > + * possibly destroys the owner along with the memory region. It does nothing if > + * the owner is not present. > + * See docs/devel/memory.rst to know about owner. > * > * @mr: the #MemoryRegion > */ > @@ -1255,7 +1252,7 @@ void memory_region_unref(MemoryRegion *mr); > * if @size is nonzero, subregions will be clipped to @size. > * > * @mr: the #MemoryRegion to be initialized. > - * @owner: the object that tracks the region's reference count > + * @owner: the object that keeps the region alive > * @ops: a structure containing read and write callbacks to be used when > * I/O is performed on the region. > * @opaque: passed to the read and write callbacks of the @ops structure. > @@ -1275,7 +1272,7 @@ void memory_region_init_io(MemoryRegion *mr, > * directly. > * > * @mr: the #MemoryRegion to be initialized. > - * @owner: the object that tracks the region's reference count > + * @owner: the object that keeps the region alive > * @name: Region name, becomes part of RAMBlock name used in migration stream > * must be unique within any device > * @size: size of the region. > @@ -1298,7 +1295,7 @@ bool memory_region_init_ram_nomigrate(MemoryRegion *mr, > * modify memory directly. > * > * @mr: the #MemoryRegion to be initialized. > - * @owner: the object that tracks the region's reference count > + * @owner: the object that keeps the region alive > * @name: Region name, becomes part of RAMBlock name used in migration stream > * must be unique within any device > * @size: size of the region. > @@ -1328,7 +1325,7 @@ bool memory_region_init_ram_flags_nomigrate(MemoryRegion *mr, > * canceled. > * > * @mr: the #MemoryRegion to be initialized. > - * @owner: the object that tracks the region's reference count > + * @owner: the object that keeps the region alive > * @name: Region name, becomes part of RAMBlock name used in migration stream > * must be unique within any device > * @size: used size of the region. > @@ -1357,7 +1354,7 @@ bool memory_region_init_resizeable_ram(MemoryRegion *mr, > * mmap-ed backend. > * > * @mr: the #MemoryRegion to be initialized. > - * @owner: the object that tracks the region's reference count > + * @owner: the object that keeps the region alive > * @name: Region name, becomes part of RAMBlock name used in migration stream > * must be unique within any device > * @size: size of the region. > @@ -1390,7 +1387,7 @@ bool memory_region_init_ram_from_file(MemoryRegion *mr, > * mmap-ed backend. > * > * @mr: the #MemoryRegion to be initialized. > - * @owner: the object that tracks the region's reference count > + * @owner: the object that keeps the region alive > * @name: the name of the region. > * @size: size of the region. > * @ram_flags: RamBlock flags. Supported flags: RAM_SHARED, RAM_PMEM, > @@ -1421,7 +1418,7 @@ bool memory_region_init_ram_from_fd(MemoryRegion *mr, > * region will modify memory directly. > * > * @mr: the #MemoryRegion to be initialized. > - * @owner: the object that tracks the region's reference count > + * @owner: the object that keeps the region alive > * @name: Region name, becomes part of RAMBlock name used in migration stream > * must be unique within any device > * @size: size of the region. > @@ -1449,7 +1446,7 @@ void memory_region_init_ram_ptr(MemoryRegion *mr, > * skip_dump flag. > * > * @mr: the #MemoryRegion to be initialized. > - * @owner: the object that tracks the region's reference count > + * @owner: the object that keeps the region alive > * @name: the name of the region. > * @size: size of the region. > * @ptr: memory to be mapped; must contain at least @size bytes. > @@ -1469,7 +1466,7 @@ void memory_region_init_ram_device_ptr(MemoryRegion *mr, > * part of another memory region. > * > * @mr: the #MemoryRegion to be initialized. > - * @owner: the object that tracks the region's reference count > + * @owner: the object that keeps the region alive > * @name: used for debugging; not visible to the user or ABI > * @orig: the region to be referenced; @mr will be equivalent to > * @orig between @offset and @offset + @size - 1. > @@ -1495,7 +1492,7 @@ void memory_region_init_alias(MemoryRegion *mr, > * of the caller. > * > * @mr: the #MemoryRegion to be initialized. > - * @owner: the object that tracks the region's reference count > + * @owner: the object that keeps the region alive > * @name: Region name, becomes part of RAMBlock name used in migration stream > * must be unique within any device > * @size: size of the region. > @@ -1518,7 +1515,7 @@ bool memory_region_init_rom_nomigrate(MemoryRegion *mr, > * of the caller. > * > * @mr: the #MemoryRegion to be initialized. > - * @owner: the object that tracks the region's reference count > + * @owner: the object that keeps the region alive > * @ops: callbacks for write access handling (must not be NULL). > * @opaque: passed to the read and write callbacks of the @ops structure. > * @name: Region name, becomes part of RAMBlock name used in migration stream > @@ -1554,7 +1551,7 @@ bool memory_region_init_rom_device_nomigrate(MemoryRegion *mr, > * @_iommu_mr: the #IOMMUMemoryRegion to be initialized > * @instance_size: the IOMMUMemoryRegion subclass instance size > * @mrtypename: the type name of the #IOMMUMemoryRegion > - * @owner: the object that tracks the region's reference count > + * @owner: the object that keeps the region alive > * @name: used for debugging; not visible to the user or ABI > * @size: size of the region. > */ > @@ -1570,7 +1567,7 @@ void memory_region_init_iommu(void *_iommu_mr, > * region will modify memory directly. > * > * @mr: the #MemoryRegion to be initialized > - * @owner: the object that tracks the region's reference count (must be > + * @owner: the object that keeps the region alive (must be > * TYPE_DEVICE or a subclass of TYPE_DEVICE, or NULL) > * @name: name of the memory region > * @size: size of the region in bytes > @@ -1616,7 +1613,7 @@ bool memory_region_init_ram_guest_memfd(MemoryRegion *mr, > * If you pass a non-NULL non-device @owner then we will assert. > * > * @mr: the #MemoryRegion to be initialized. > - * @owner: the object that tracks the region's reference count > + * @owner: the object that keeps the region alive > * @name: Region name, becomes part of RAMBlock name used in migration stream > * must be unique within any device > * @size: size of the region. > @@ -1647,7 +1644,7 @@ bool memory_region_init_rom(MemoryRegion *mr, > * If you pass a non-NULL non-device @owner then we will assert. > * > * @mr: the #MemoryRegion to be initialized. > - * @owner: the object that tracks the region's reference count > + * @owner: the object that keeps the region alive > * @ops: callbacks for write access handling (must not be NULL). > * @opaque: passed to the read and write callbacks of the @ops structure. > * @name: Region name, becomes part of RAMBlock name used in migration stream > >
On Thu, Jan 09, 2025 at 01:30:35PM +0100, BALATON Zoltan wrote: > On Thu, 9 Jan 2025, Akihiko Odaki wrote: > > Do not refer to "memory region's reference count" > > ------------------------------------------------- > > > > Now MemoryRegions do have their own reference counts, but they will not > > be used when their owners are not themselves. However, the documentation > > of memory_region_ref() says it adds "1 to a memory region's reference > > count", which is confusing. Avoid referring to "memory region's > > reference count" and just say: "Add a reference to a memory region". > > Make a similar change to memory_region_unref() too. > > > > Refer to docs/devel/memory.rst for "owner" > > ------------------------------------------ > > > > memory_region_ref() and memory_region_unref() used to have their own > > descriptions of "owner", but they are somewhat out-of-date and > > misleading. > > > > In particular, they say "whenever memory regions are accessed outside > > the BQL, they need to be preserved against hot-unplug", but protecting > > against hot-unplug is not mandatory if it is known that they will never > > be hot-unplugged. They also say "MemoryRegions actually do not have > > their own reference count", but they actually do. They just will not be > > used unless their owners are not themselves. > > > > Refer to docs/devel/memory.rst as the single source of truth instead of > > maintaining duplicate descriptions of "owner". > > > > Clarify that owner may be missing > > > > --------------------------------- > > A memory region may not have an owner, and memory_region_ref() and > > memory_region_unref() do nothing for such. > > > > memory: Clarify owner must not call memory_region_ref() > > -------------------------------------------------------- > > > > The owner must not call this function as it results in a circular > > reference. > > > > Signed-off-by: Akihiko Odaki <akihiko.odaki@daynix.com> > > Reviewed-by: Peter Xu <peterx@redhat.com> > > --- > > include/exec/memory.h | 59 ++++++++++++++++++++++++--------------------------- > > 1 file changed, 28 insertions(+), 31 deletions(-) > > > > diff --git a/include/exec/memory.h b/include/exec/memory.h > > index 9458e2801d50..ca247343f433 100644 > > --- a/include/exec/memory.h > > +++ b/include/exec/memory.h > > @@ -1210,7 +1210,7 @@ void memory_region_section_free_copy(MemoryRegionSection *s); > > * memory_region_add_subregion() to add subregions. > > * > > * @mr: the #MemoryRegion to be initialized > > - * @owner: the object that tracks the region's reference count > > + * @owner: the object that keeps the region alive > > * @name: used for debugging; not visible to the user or ABI > > * @size: size of the region; any subregions beyond this size will be clipped > > */ > > @@ -1220,29 +1220,26 @@ void memory_region_init(MemoryRegion *mr, > > uint64_t size); > > > > /** > > - * memory_region_ref: Add 1 to a memory region's reference count > > + * memory_region_ref: Add a reference to the owner of a memory region > > * > > - * Whenever memory regions are accessed outside the BQL, they need to be > > - * preserved against hot-unplug. MemoryRegions actually do not have their > > - * own reference count; they piggyback on a QOM object, their "owner". > > - * This function adds a reference to the owner. > > - * > > - * All MemoryRegions must have an owner if they can disappear, even if the > > - * device they belong to operates exclusively under the BQL. This is because > > - * the region could be returned at any time by memory_region_find, and this > > - * is usually under guest control. > > + * This function adds a reference to the owner of a memory region to keep the > > + * memory region alive. It does nothing if the owner is not present as a memory > > + * region without owner will never die. > > + * For references internal to the owner, use object_ref() instead to avoid a > > + * circular reference. > > Reading this again I'm still confused by this last sentence. Do you mean > references internal to the memory region should use object_ref on the memory > region or that other references to the owner should use object_ref on the > owner? This sentence is still not clear about that. Having two refcounts are definitely confusing.. especially IIRC all MRs' obj->free==NULL, so the MR's refcount isn't working. Dynamic MR's needs its g_free() on its own. I acked both patches, but maybe it could indeed be slightly better we drop this sentence, meanwhile in patch 2 we can drop the object_ref() too: it means for parent/child MRs that share the same owner, QEMU does nothing on the child MRs when add subregion, because it assumes the child MR will never go away when the parent is there who shares the owner. So maybe we try not to touch MR's refcount manually, but fix what can be problematic for owner->ref only.
On Thu, Jan 09, 2025 at 02:29:21PM -0500, Peter Xu wrote: > On Thu, Jan 09, 2025 at 01:30:35PM +0100, BALATON Zoltan wrote: > > On Thu, 9 Jan 2025, Akihiko Odaki wrote: > > > Do not refer to "memory region's reference count" > > > ------------------------------------------------- > > > > > > Now MemoryRegions do have their own reference counts, but they will not > > > be used when their owners are not themselves. However, the documentation > > > of memory_region_ref() says it adds "1 to a memory region's reference > > > count", which is confusing. Avoid referring to "memory region's > > > reference count" and just say: "Add a reference to a memory region". > > > Make a similar change to memory_region_unref() too. > > > > > > Refer to docs/devel/memory.rst for "owner" > > > ------------------------------------------ > > > > > > memory_region_ref() and memory_region_unref() used to have their own > > > descriptions of "owner", but they are somewhat out-of-date and > > > misleading. > > > > > > In particular, they say "whenever memory regions are accessed outside > > > the BQL, they need to be preserved against hot-unplug", but protecting > > > against hot-unplug is not mandatory if it is known that they will never > > > be hot-unplugged. They also say "MemoryRegions actually do not have > > > their own reference count", but they actually do. They just will not be > > > used unless their owners are not themselves. > > > > > > Refer to docs/devel/memory.rst as the single source of truth instead of > > > maintaining duplicate descriptions of "owner". > > > > > > Clarify that owner may be missing > > > > > > --------------------------------- > > > A memory region may not have an owner, and memory_region_ref() and > > > memory_region_unref() do nothing for such. > > > > > > memory: Clarify owner must not call memory_region_ref() > > > -------------------------------------------------------- > > > > > > The owner must not call this function as it results in a circular > > > reference. > > > > > > Signed-off-by: Akihiko Odaki <akihiko.odaki@daynix.com> > > > Reviewed-by: Peter Xu <peterx@redhat.com> > > > --- > > > include/exec/memory.h | 59 ++++++++++++++++++++++++--------------------------- > > > 1 file changed, 28 insertions(+), 31 deletions(-) > > > > > > diff --git a/include/exec/memory.h b/include/exec/memory.h > > > index 9458e2801d50..ca247343f433 100644 > > > --- a/include/exec/memory.h > > > +++ b/include/exec/memory.h > > > @@ -1210,7 +1210,7 @@ void memory_region_section_free_copy(MemoryRegionSection *s); > > > * memory_region_add_subregion() to add subregions. > > > * > > > * @mr: the #MemoryRegion to be initialized > > > - * @owner: the object that tracks the region's reference count > > > + * @owner: the object that keeps the region alive > > > * @name: used for debugging; not visible to the user or ABI > > > * @size: size of the region; any subregions beyond this size will be clipped > > > */ > > > @@ -1220,29 +1220,26 @@ void memory_region_init(MemoryRegion *mr, > > > uint64_t size); > > > > > > /** > > > - * memory_region_ref: Add 1 to a memory region's reference count > > > + * memory_region_ref: Add a reference to the owner of a memory region > > > * > > > - * Whenever memory regions are accessed outside the BQL, they need to be > > > - * preserved against hot-unplug. MemoryRegions actually do not have their > > > - * own reference count; they piggyback on a QOM object, their "owner". > > > - * This function adds a reference to the owner. > > > - * > > > - * All MemoryRegions must have an owner if they can disappear, even if the > > > - * device they belong to operates exclusively under the BQL. This is because > > > - * the region could be returned at any time by memory_region_find, and this > > > - * is usually under guest control. > > > + * This function adds a reference to the owner of a memory region to keep the > > > + * memory region alive. It does nothing if the owner is not present as a memory > > > + * region without owner will never die. > > > + * For references internal to the owner, use object_ref() instead to avoid a > > > + * circular reference. > > > > Reading this again I'm still confused by this last sentence. Do you mean > > references internal to the memory region should use object_ref on the memory > > region or that other references to the owner should use object_ref on the > > owner? This sentence is still not clear about that. > > Having two refcounts are definitely confusing.. especially IIRC all MRs' > obj->free==NULL, so the MR's refcount isn't working. Dynamic MR's needs > its g_free() on its own. > > I acked both patches, but maybe it could indeed be slightly better we drop > this sentence, meanwhile in patch 2 we can drop the object_ref() too: it > means for parent/child MRs that share the same owner, QEMU does nothing on > the child MRs when add subregion, because it assumes the child MR will > never go away when the parent is there who shares the owner. > > So maybe we try not to touch MR's refcount manually, but fix what can be > problematic for owner->ref only. As an attached comment: I may have forgot some context on this issue, but I still remember I used to have a patch that simply detach either parent or child MR links when finalize(). It's here: https://lore.kernel.org/all/ZsenKpu1czQGYz7m@x1n/ I see this issue was there for a long time so maybe we want to fix it one way or another. I don't strongly feel which way to go, but personally I still prefer that way (I assume that can fix the same issue), and it doesn't have MR's refcount involved at all, meanwhile I don't see an issue yet with it..
diff --git a/include/exec/memory.h b/include/exec/memory.h index 9458e2801d50..ca247343f433 100644 --- a/include/exec/memory.h +++ b/include/exec/memory.h @@ -1210,7 +1210,7 @@ void memory_region_section_free_copy(MemoryRegionSection *s); * memory_region_add_subregion() to add subregions. * * @mr: the #MemoryRegion to be initialized - * @owner: the object that tracks the region's reference count + * @owner: the object that keeps the region alive * @name: used for debugging; not visible to the user or ABI * @size: size of the region; any subregions beyond this size will be clipped */ @@ -1220,29 +1220,26 @@ void memory_region_init(MemoryRegion *mr, uint64_t size); /** - * memory_region_ref: Add 1 to a memory region's reference count + * memory_region_ref: Add a reference to the owner of a memory region * - * Whenever memory regions are accessed outside the BQL, they need to be - * preserved against hot-unplug. MemoryRegions actually do not have their - * own reference count; they piggyback on a QOM object, their "owner". - * This function adds a reference to the owner. - * - * All MemoryRegions must have an owner if they can disappear, even if the - * device they belong to operates exclusively under the BQL. This is because - * the region could be returned at any time by memory_region_find, and this - * is usually under guest control. + * This function adds a reference to the owner of a memory region to keep the + * memory region alive. It does nothing if the owner is not present as a memory + * region without owner will never die. + * For references internal to the owner, use object_ref() instead to avoid a + * circular reference. + * See docs/devel/memory.rst to know about owner. * * @mr: the #MemoryRegion */ void memory_region_ref(MemoryRegion *mr); /** - * memory_region_unref: Remove 1 to a memory region's reference count + * memory_region_unref: Remove a reference to the memory region of the owner * - * Whenever memory regions are accessed outside the BQL, they need to be - * preserved against hot-unplug. MemoryRegions actually do not have their - * own reference count; they piggyback on a QOM object, their "owner". - * This function removes a reference to the owner and possibly destroys it. + * This function removes a reference to the owner of a memory region and + * possibly destroys the owner along with the memory region. It does nothing if + * the owner is not present. + * See docs/devel/memory.rst to know about owner. * * @mr: the #MemoryRegion */ @@ -1255,7 +1252,7 @@ void memory_region_unref(MemoryRegion *mr); * if @size is nonzero, subregions will be clipped to @size. * * @mr: the #MemoryRegion to be initialized. - * @owner: the object that tracks the region's reference count + * @owner: the object that keeps the region alive * @ops: a structure containing read and write callbacks to be used when * I/O is performed on the region. * @opaque: passed to the read and write callbacks of the @ops structure. @@ -1275,7 +1272,7 @@ void memory_region_init_io(MemoryRegion *mr, * directly. * * @mr: the #MemoryRegion to be initialized. - * @owner: the object that tracks the region's reference count + * @owner: the object that keeps the region alive * @name: Region name, becomes part of RAMBlock name used in migration stream * must be unique within any device * @size: size of the region. @@ -1298,7 +1295,7 @@ bool memory_region_init_ram_nomigrate(MemoryRegion *mr, * modify memory directly. * * @mr: the #MemoryRegion to be initialized. - * @owner: the object that tracks the region's reference count + * @owner: the object that keeps the region alive * @name: Region name, becomes part of RAMBlock name used in migration stream * must be unique within any device * @size: size of the region. @@ -1328,7 +1325,7 @@ bool memory_region_init_ram_flags_nomigrate(MemoryRegion *mr, * canceled. * * @mr: the #MemoryRegion to be initialized. - * @owner: the object that tracks the region's reference count + * @owner: the object that keeps the region alive * @name: Region name, becomes part of RAMBlock name used in migration stream * must be unique within any device * @size: used size of the region. @@ -1357,7 +1354,7 @@ bool memory_region_init_resizeable_ram(MemoryRegion *mr, * mmap-ed backend. * * @mr: the #MemoryRegion to be initialized. - * @owner: the object that tracks the region's reference count + * @owner: the object that keeps the region alive * @name: Region name, becomes part of RAMBlock name used in migration stream * must be unique within any device * @size: size of the region. @@ -1390,7 +1387,7 @@ bool memory_region_init_ram_from_file(MemoryRegion *mr, * mmap-ed backend. * * @mr: the #MemoryRegion to be initialized. - * @owner: the object that tracks the region's reference count + * @owner: the object that keeps the region alive * @name: the name of the region. * @size: size of the region. * @ram_flags: RamBlock flags. Supported flags: RAM_SHARED, RAM_PMEM, @@ -1421,7 +1418,7 @@ bool memory_region_init_ram_from_fd(MemoryRegion *mr, * region will modify memory directly. * * @mr: the #MemoryRegion to be initialized. - * @owner: the object that tracks the region's reference count + * @owner: the object that keeps the region alive * @name: Region name, becomes part of RAMBlock name used in migration stream * must be unique within any device * @size: size of the region. @@ -1449,7 +1446,7 @@ void memory_region_init_ram_ptr(MemoryRegion *mr, * skip_dump flag. * * @mr: the #MemoryRegion to be initialized. - * @owner: the object that tracks the region's reference count + * @owner: the object that keeps the region alive * @name: the name of the region. * @size: size of the region. * @ptr: memory to be mapped; must contain at least @size bytes. @@ -1469,7 +1466,7 @@ void memory_region_init_ram_device_ptr(MemoryRegion *mr, * part of another memory region. * * @mr: the #MemoryRegion to be initialized. - * @owner: the object that tracks the region's reference count + * @owner: the object that keeps the region alive * @name: used for debugging; not visible to the user or ABI * @orig: the region to be referenced; @mr will be equivalent to * @orig between @offset and @offset + @size - 1. @@ -1495,7 +1492,7 @@ void memory_region_init_alias(MemoryRegion *mr, * of the caller. * * @mr: the #MemoryRegion to be initialized. - * @owner: the object that tracks the region's reference count + * @owner: the object that keeps the region alive * @name: Region name, becomes part of RAMBlock name used in migration stream * must be unique within any device * @size: size of the region. @@ -1518,7 +1515,7 @@ bool memory_region_init_rom_nomigrate(MemoryRegion *mr, * of the caller. * * @mr: the #MemoryRegion to be initialized. - * @owner: the object that tracks the region's reference count + * @owner: the object that keeps the region alive * @ops: callbacks for write access handling (must not be NULL). * @opaque: passed to the read and write callbacks of the @ops structure. * @name: Region name, becomes part of RAMBlock name used in migration stream @@ -1554,7 +1551,7 @@ bool memory_region_init_rom_device_nomigrate(MemoryRegion *mr, * @_iommu_mr: the #IOMMUMemoryRegion to be initialized * @instance_size: the IOMMUMemoryRegion subclass instance size * @mrtypename: the type name of the #IOMMUMemoryRegion - * @owner: the object that tracks the region's reference count + * @owner: the object that keeps the region alive * @name: used for debugging; not visible to the user or ABI * @size: size of the region. */ @@ -1570,7 +1567,7 @@ void memory_region_init_iommu(void *_iommu_mr, * region will modify memory directly. * * @mr: the #MemoryRegion to be initialized - * @owner: the object that tracks the region's reference count (must be + * @owner: the object that keeps the region alive (must be * TYPE_DEVICE or a subclass of TYPE_DEVICE, or NULL) * @name: name of the memory region * @size: size of the region in bytes @@ -1616,7 +1613,7 @@ bool memory_region_init_ram_guest_memfd(MemoryRegion *mr, * If you pass a non-NULL non-device @owner then we will assert. * * @mr: the #MemoryRegion to be initialized. - * @owner: the object that tracks the region's reference count + * @owner: the object that keeps the region alive * @name: Region name, becomes part of RAMBlock name used in migration stream * must be unique within any device * @size: size of the region. @@ -1647,7 +1644,7 @@ bool memory_region_init_rom(MemoryRegion *mr, * If you pass a non-NULL non-device @owner then we will assert. * * @mr: the #MemoryRegion to be initialized. - * @owner: the object that tracks the region's reference count + * @owner: the object that keeps the region alive * @ops: callbacks for write access handling (must not be NULL). * @opaque: passed to the read and write callbacks of the @ops structure. * @name: Region name, becomes part of RAMBlock name used in migration stream