From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:53275) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1XKjSW-0000M7-VD for qemu-devel@nongnu.org; Fri, 22 Aug 2014 03:40:34 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1XKjSM-0004qY-NV for qemu-devel@nongnu.org; Fri, 22 Aug 2014 03:40:28 -0400 Received: from mx-v6.kamp.de ([2a02:248:0:51::16]:34334 helo=mx01.kamp.de) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1XKjSM-0004qK-Ck for qemu-devel@nongnu.org; Fri, 22 Aug 2014 03:40:18 -0400 Message-ID: <53F6F3DD.2090804@kamp.de> Date: Fri, 22 Aug 2014 09:40:13 +0200 From: Peter Lieven MIME-Version: 1.0 References: <00c425bd67fc66567dc683205f8f60f7.squirrel@ssl.dlhnet.de> In-Reply-To: <00c425bd67fc66567dc683205f8f60f7.squirrel@ssl.dlhnet.de> Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [Fwd: [PATCH v4 07/21] iscsi: Handle failure for potentially large allocations] List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Kevin Wolf Cc: benoit.canet@irqsave.net, Paolo Bonzini , maxa@catit.be, qemu-devel@nongnu.org, stefanha@redhat.com Am 22.08.2014 um 09:35 schrieb Peter Lieven: > Some code in the block layer makes potentially huge allocations. Failure > is not completely unexpected there, so avoid aborting qemu and handle > out-of-memory situations gracefully. > > This patch addresses the allocations in the iscsi block driver. > > Signed-off-by: Kevin Wolf > Acked-by: Paolo Bonzini > Reviewed-by: Benoit Canet > Reviewed-by: Eric Blake > --- > block/iscsi.c | 5 ++++- > 1 file changed, 4 insertions(+), 1 deletion(-) > > diff --git a/block/iscsi.c b/block/iscsi.c > index 84aa22a..06afa78 100644 > --- a/block/iscsi.c > +++ b/block/iscsi.c > @@ -893,7 +893,10 @@ coroutine_fn iscsi_co_write_zeroes(BlockDriverState > *bs, int64_t sector_num, > nb_blocks = sector_qemu2lun(nb_sectors, iscsilun); > > if (iscsilun->zeroblock == NULL) { > - iscsilun->zeroblock = g_malloc0(iscsilun->block_size); > + iscsilun->zeroblock = g_try_malloc0(iscsilun->block_size); > + if (iscsilun->zeroblock == NULL) { > + return -ENOMEM; > + } > } > > iscsi_co_init_iscsitask(iscsilun, &iTask); Unfortunately, I missed that one. The zeroblock is typicalls 512 Byte or 4K depending on the blocksize. What is significantly larger is the allocationmap. It is typically created on iscsi_open, but is also recreated on iscsi_truncate. I don't have the context why this patch was introduced, but I would vote for introducing a bitmap_try_new and issue a warning if the allocation fails. The allocationmap is optional we can work without it. If the pointer is NULL its not used. Peter