From f70d3451fe468eacddb15ccf5fd170754510b0a0 Mon Sep 17 00:00:00 2001 From: "Dr. David Alan Gilbert" Date: Mon, 24 Jul 2017 17:51:25 +0100 Subject: [PATCH] cpu_physical_memory_sync_dirty_bitmap: Fix alignment check MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit This code has an optimised, word aligned version, and a boring unaligned version. Recently 084140bd498909 fixed a missing offset addition from the core of both versions. However, the offset isn't necessarily aligned and thus the choice between the two versions needs fixing up to also include the offset. Symptom: A few stuck unsent pages during migration; not normally noticed unless under very low bandwidth in which case the migration may get stuck never ending and never performing a 2nd sync; noticed by a hanging postcopy-test on a very heavily loaded system. Fixes: 084140bd498909 Signed-off-by: Dr. David Alan Gilbert Reported-by: Alex Benneé Tested-by: Alex Benneé -- v2 Move 'page' inside the if (Comment from Paolo) Message-Id: <20170724165125.29887-1-dgilbert@redhat.com> Signed-off-by: Paolo Bonzini --- include/exec/ram_addr.h | 7 ++++--- 1 file changed, 4 insertions(+), 3 deletions(-) diff --git a/include/exec/ram_addr.h b/include/exec/ram_addr.h index c04f4f67f6..d017639f7e 100644 --- a/include/exec/ram_addr.h +++ b/include/exec/ram_addr.h @@ -377,19 +377,20 @@ uint64_t cpu_physical_memory_sync_dirty_bitmap(RAMBlock *rb, uint64_t *real_dirty_pages) { ram_addr_t addr; - unsigned long page = BIT_WORD(start >> TARGET_PAGE_BITS); + unsigned long word = BIT_WORD((start + rb->offset) >> TARGET_PAGE_BITS); uint64_t num_dirty = 0; unsigned long *dest = rb->bmap; /* start address is aligned at the start of a word? */ - if (((page * BITS_PER_LONG) << TARGET_PAGE_BITS) == start) { + if (((word * BITS_PER_LONG) << TARGET_PAGE_BITS) == + (start + rb->offset)) { int k; int nr = BITS_TO_LONGS(length >> TARGET_PAGE_BITS); unsigned long * const *src; - unsigned long word = BIT_WORD((start + rb->offset) >> TARGET_PAGE_BITS); unsigned long idx = (word * BITS_PER_LONG) / DIRTY_MEMORY_BLOCK_SIZE; unsigned long offset = BIT_WORD((word * BITS_PER_LONG) % DIRTY_MEMORY_BLOCK_SIZE); + unsigned long page = BIT_WORD(start >> TARGET_PAGE_BITS); rcu_read_lock();