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envelope-from=farosas@suse.de; helo=smtp-out2.suse.de X-Spam_score_int: -43 X-Spam_score: -4.4 X-Spam_bar: ---- X-Spam_report: (-4.4 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_MED=-2.3, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Prasad Pandit writes: > From: Prasad Pandit > > During multifd migration, zero pages are are written if > they are migrated more than ones. s/ones/once/ > > This may result in a migration hang issue when Multifd > and Postcopy are enabled together. > > When Postcopy is enabled, always write zero pages as and > when they are migrated. > > Signed-off-by: Prasad Pandit This patch should come before 1/3, otherwise it'll break bisect. > --- > migration/multifd-zero-page.c | 22 ++++++++++++++++++++-- > 1 file changed, 20 insertions(+), 2 deletions(-) > > v10: new patch, not present in v9 or earlier versions. > > diff --git a/migration/multifd-zero-page.c b/migration/multifd-zero-page.c > index dbc1184921..9bfb3ef803 100644 > --- a/migration/multifd-zero-page.c > +++ b/migration/multifd-zero-page.c > @@ -85,9 +85,27 @@ void multifd_recv_zero_page_process(MultiFDRecvParams *p) > { > for (int i = 0; i < p->zero_num; i++) { > void *page = p->host + p->zero[i]; > - if (ramblock_recv_bitmap_test_byte_offset(p->block, p->zero[i])) { > + > + /* > + * During multifd migration zero page is written to the memory > + * only if it is migrated more than ones. s/ones/once/ > + * > + * It becomes a problem when both Multifd & Postcopy options are > + * enabled. If the zero page which was skipped during multifd phase, > + * is accessed during the Postcopy phase of the migration, a page > + * fault occurs. But this page fault is not served because the > + * 'receivedmap' says the zero page is already received. Thus the > + * migration hangs. > + * > + * When Postcopy is enabled, always write the zero page as and when > + * it is migrated. > + * extra blank line here^ > + */ nit: Inconsistent use of capitalization for the feature names. I'd keep it all lowercase. > + if (migrate_postcopy_ram() || > + ramblock_recv_bitmap_test_byte_offset(p->block, p->zero[i])) { > memset(page, 0, multifd_ram_page_size()); > - } else { > + } > + if (!ramblock_recv_bitmap_test_byte_offset(p->block, p->zero[i])) { > ramblock_recv_bitmap_set_offset(p->block, p->zero[i]); > } > }