| Message ID | 20241218091413.140396-2-yuan1.liu@intel.com (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | bugfixes for migration using compression methods | expand |
On Wed, Dec 18, 2024 at 05:14:11PM +0800, Yuan Liu wrote: > When compression is enabled on the migration channel and > the pages processed are all zero pages, these pages will > not be sent and updated on the target side, resulting in > incorrect memory data on the source and target sides. > > The root cause is that all compression methods call > multifd_send_prepare_common to determine whether to compress > dirty pages, but multifd_send_prepare_common does not update > the IOV of MultiFDPacket_t when all dirty pages are zero pages. > > The solution is to always update the IOV of MultiFDPacket_t > regardless of whether the dirty pages are all zero pages. > > Signed-off-by: Yuan Liu <yuan1.liu@intel.com> > Reviewed-by: Jason Zeng <jason.zeng@intel.com> Ouch.. thanks for digging this out. Reviewed-by: Peter Xu <peterx@redhat.com> Is this the correct Fixes tag (and copy stable for 9.0+)? Fixes: 303e6f54f9 ("migration/multifd: Implement zero page transmission on the multifd thread.") > --- > migration/multifd-nocomp.c | 3 +-- > 1 file changed, 1 insertion(+), 2 deletions(-) > > diff --git a/migration/multifd-nocomp.c b/migration/multifd-nocomp.c > index 55191152f9..2e4aaac285 100644 > --- a/migration/multifd-nocomp.c > +++ b/migration/multifd-nocomp.c > @@ -362,6 +362,7 @@ int multifd_ram_flush_and_sync(void) > bool multifd_send_prepare_common(MultiFDSendParams *p) > { > MultiFDPages_t *pages = &p->data->u.ram; > + multifd_send_prepare_header(p); > multifd_send_zero_page_detect(p); > > if (!pages->normal_num) { > @@ -369,8 +370,6 @@ bool multifd_send_prepare_common(MultiFDSendParams *p) > return false; > } > > - multifd_send_prepare_header(p); > - > return true; > } > > -- > 2.43.0 >
> -----Original Message----- > From: Peter Xu <peterx@redhat.com> > Sent: Thursday, December 19, 2024 1:03 AM > To: Liu, Yuan1 <yuan1.liu@intel.com> > Cc: farosas@suse.de; qemu-devel@nongnu.org; Zeng, Jason > <jason.zeng@intel.com>; Wang, Yichen <yichen.wang@bytedance.com> > Subject: Re: [PATCH 1/3] multifd: bugfix for migration using compression > methods > > On Wed, Dec 18, 2024 at 05:14:11PM +0800, Yuan Liu wrote: > > When compression is enabled on the migration channel and > > the pages processed are all zero pages, these pages will > > not be sent and updated on the target side, resulting in > > incorrect memory data on the source and target sides. > > > > The root cause is that all compression methods call > > multifd_send_prepare_common to determine whether to compress > > dirty pages, but multifd_send_prepare_common does not update > > the IOV of MultiFDPacket_t when all dirty pages are zero pages. > > > > The solution is to always update the IOV of MultiFDPacket_t > > regardless of whether the dirty pages are all zero pages. > > > > Signed-off-by: Yuan Liu <yuan1.liu@intel.com> > > Reviewed-by: Jason Zeng <jason.zeng@intel.com> > > Ouch.. thanks for digging this out. > > Reviewed-by: Peter Xu <peterx@redhat.com> > > Is this the correct Fixes tag (and copy stable for 9.0+)? > > Fixes: 303e6f54f9 ("migration/multifd: Implement zero page transmission on > the multifd thread.") Yes, this patch is used to fix the tag containing 303e6f54f9, and I see it already exists in v9.0.0 and later versions. By the way, The three bugfix patches are based on mainline and the commit id is 8032c78e55 (origin/staging, origin/master, origin/HEAD) Merge tag 'firmware-20241216-pull-request' of https://gitlab.com/kraxel/qemu into staging > > --- > > migration/multifd-nocomp.c | 3 +-- > > 1 file changed, 1 insertion(+), 2 deletions(-) > > > > diff --git a/migration/multifd-nocomp.c b/migration/multifd-nocomp.c > > index 55191152f9..2e4aaac285 100644 > > --- a/migration/multifd-nocomp.c > > +++ b/migration/multifd-nocomp.c > > @@ -362,6 +362,7 @@ int multifd_ram_flush_and_sync(void) > > bool multifd_send_prepare_common(MultiFDSendParams *p) > > { > > MultiFDPages_t *pages = &p->data->u.ram; > > + multifd_send_prepare_header(p); > > multifd_send_zero_page_detect(p); > > > > if (!pages->normal_num) { > > @@ -369,8 +370,6 @@ bool multifd_send_prepare_common(MultiFDSendParams > *p) > > return false; > > } > > > > - multifd_send_prepare_header(p); > > - > > return true; > > } > > > > -- > > 2.43.0 > > > > -- > Peter Xu
diff --git a/migration/multifd-nocomp.c b/migration/multifd-nocomp.c index 55191152f9..2e4aaac285 100644 --- a/migration/multifd-nocomp.c +++ b/migration/multifd-nocomp.c @@ -362,6 +362,7 @@ int multifd_ram_flush_and_sync(void) bool multifd_send_prepare_common(MultiFDSendParams *p) { MultiFDPages_t *pages = &p->data->u.ram; + multifd_send_prepare_header(p); multifd_send_zero_page_detect(p); if (!pages->normal_num) { @@ -369,8 +370,6 @@ bool multifd_send_prepare_common(MultiFDSendParams *p) return false; } - multifd_send_prepare_header(p); - return true; }