From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: From: peter chang Subject: [PATCH] fix memory allocation in the cases we may need to align Date: Wed, 24 Apr 2013 14:55:45 -0700 Message-Id: <1366840545-11768-1-git-send-email-dpf@google.com> To: axboe@kernel.dk Cc: gwendal@google.com, fio@vger.kernel.org, peter chang List-ID: when using the sg backend we crash w/ a SEGV in fio_sgio_getevents() because of memory corruption from the IO. when we allocate the td's backing store there's a possible post-allocation adjustment to page align the buffers. however, the extra memory that this alignment may need is not taken into account when allocating the buffer. Tested: - the problematic fio file looks like fdha347:~# cat foo.fio [global] bs=64k thread rw=read size=100g time_based=1 runtime=60 iodepth=1 [sdc] ioengine=sg filename=/dev/sg2 numjobs=1 Signed-off-by: peter chang --- backend.c | 9 +++++++++ 1 file changed, 9 insertions(+) diff --git a/backend.c b/backend.c index 1c4484b..f48b43d 100644 --- a/backend.c +++ b/backend.c @@ -910,6 +910,15 @@ static int init_io_u(struct thread_data *td) if ((td->io_ops->flags & FIO_NOIO) || !(td_read(td) || td_write(td))) data_xfer = 0; + /* + * if we may later need to do address alignment, then add any + * possible adjustment here so that we don't cause a buffer + * overflow later. this adjustment may be too much if we get + * lucky and the allocator gives us an aligned address. + */ + if (td->o.odirect || td->o.mem_align || (td->io_ops->flags & FIO_RAWIO)) + td->orig_buffer_size += page_mask + td->o.mem_align; + if (td->o.mem_type == MEM_SHMHUGE || td->o.mem_type == MEM_MMAPHUGE) { unsigned long bs; -- 1.8.2.1