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bh=XtdIvl849NtSwhObgAWNC1HihBCNlWbPsoigE9tqXac=; b=MaIYQea3aBJRMF9gkDz1XevwCAoFT7m7AX+l4KlXH+txUgbajpQDILpzvtwiKyOmyXDTic xCUoWGz2QsjyB73sodLfuRvNx4XBc0CP3B59AfnM9keDQ5PNE25GvkYy19JRvl0SB9tb7F pTx13fcc940HMW7qH8SEivo2GpAPI3Y= X-MC-Unique: KLWDt_O2ON24o01P_EUM7Q-1 From: David Hildenbrand To: qemu-devel@nongnu.org Subject: [PATCH v3 02/12] softmmu/physmem: Fix ram_block_discard_range() to handle shared anonymous memory Date: Mon, 8 Mar 2021 16:05:50 +0100 Message-Id: <20210308150600.14440-3-david@redhat.com> In-Reply-To: <20210308150600.14440-1-david@redhat.com> References: <20210308150600.14440-1-david@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.14 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=david@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Transfer-Encoding: quoted-printable Received-SPF: pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) client-ip=209.51.188.17; envelope-from=qemu-devel-bounces+importer=patchew.org@nongnu.org; helo=lists.gnu.org; Received-SPF: pass client-ip=216.205.24.124; envelope-from=david@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -29 X-Spam_score: -3.0 X-Spam_bar: --- X-Spam_report: (-3.0 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.251, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_LOW=-0.7, RCVD_IN_MSPIKE_H3=0.001, RCVD_IN_MSPIKE_WL=0.001, 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: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Marcel Apfelbaum , Murilo Opsfelder Araujo , Cornelia Huck , Eduardo Habkost , "Michael S. Tsirkin" , Stefan Weil , David Hildenbrand , Richard Henderson , "Dr. David Alan Gilbert" , Peter Xu , Greg Kurz , Halil Pasic , Christian Borntraeger , Stefan Hajnoczi , Igor Mammedov , Thomas Huth , Paolo Bonzini , =?UTF-8?q?Philippe=20Mathieu-Daud=C3=A9?= , Igor Kotrasinski , Juan Quintela Errors-To: qemu-devel-bounces+importer=patchew.org@nongnu.org Sender: "Qemu-devel" X-ZohoMail-DKIM: fail (Header signature does not verify) Content-Type: text/plain; charset="utf-8" We can create shared anonymous memory via "-object memory-backend-ram,share=3Don,..." which is, for example, required by PVRDMA for mremap() to work. Shared anonymous memory is weird, though. Instead of MADV_DONTNEED, we have to use MADV_REMOVE. MADV_DONTNEED fails silently and does nothing. Fixes: 06329ccecfa0 ("mem: add share parameter to memory-backend-ram") Signed-off-by: David Hildenbrand Reviewed-by: Dr. David Alan Gilbert Reviewed-by: Peter Xu --- softmmu/physmem.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) diff --git a/softmmu/physmem.c b/softmmu/physmem.c index 62ea4abbdd..2ba815fec6 100644 --- a/softmmu/physmem.c +++ b/softmmu/physmem.c @@ -3506,6 +3506,7 @@ int ram_block_discard_range(RAMBlock *rb, uint64_t st= art, size_t length) /* The logic here is messy; * madvise DONTNEED fails for hugepages * fallocate works on hugepages and shmem + * shared anonymous memory requires madvise REMOVE */ need_madvise =3D (rb->page_size =3D=3D qemu_host_page_size); need_fallocate =3D rb->fd !=3D -1; @@ -3539,7 +3540,11 @@ int ram_block_discard_range(RAMBlock *rb, uint64_t s= tart, size_t length) * fallocate'd away). */ #if defined(CONFIG_MADVISE) - ret =3D madvise(host_startaddr, length, MADV_DONTNEED); + if (qemu_ram_is_shared(rb) && rb->fd < 0) { + ret =3D madvise(host_startaddr, length, MADV_REMOVE); + } else { + ret =3D madvise(host_startaddr, length, MADV_DONTNEED); + } if (ret) { ret =3D -errno; error_report("ram_block_discard_range: Failed to discard r= ange " --=20 2.29.2