On Sat, Aug 27, 2022 at 12:57:50PM +0300, Dmitry Kozlyuk wrote:
> 2022-08-27 09:25 (UTC+0000), chengt...@qq.com:
> > From: lic121 <lic...@chinatelecom.cn>
> >
> > When RTE_MALLOC_DEBUG not configured, rte_zmalloc_socket() doens't
> > zero oute allocaed memory. Because memory are zeroed out when free
> > in malloc_elem_free(). But seems the initial allocated memory is
> > not zeroed out as expected.
> >
> > This patch zero out initial allocated memory in
> > malloc_heap_add_memory().
> >
> > With dpdk 20.11.5, "QLogic Corp. FastLinQ QL41000" probe triggers
> > this problem.
> > ```
> > Stack trace of thread 412780:
> > #0 0x0000000000e5fb99 ecore_int_igu_read_cam (dpdk-testpmd)
> > #1 0x0000000000e4df54 ecore_get_hw_info (dpdk-testpmd)
> > #2 0x0000000000e504aa ecore_hw_prepare (dpdk-testpmd)
> > #3 0x0000000000e8a7ca qed_probe (dpdk-testpmd)
> > #4 0x0000000000e83c59 qede_common_dev_init (dpdk-testpmd)
> > #5 0x0000000000e84c8e qede_eth_dev_init (dpdk-testpmd)
> > #6 0x00000000009dd5a7 rte_pci_probe_one_driver (dpdk-testpmd)
> > #7 0x00000000009734e3 rte_bus_probe (dpdk-testpmd)
> > #8 0x00000000009933bd rte_eal_init (dpdk-testpmd)
> > #9 0x000000000041768f main (dpdk-testpmd)
> > #10 0x00007f41a7001b17 __libc_start_main (libc.so.6)
> > #11 0x000000000067e34a _start (dpdk-testpmd)
> > ```
> >
> > Signed-off-by: lic121 <lic...@chinatelecom.cn>
> > ---
> > lib/librte_eal/common/malloc_heap.c | 8 ++++++++
> > 1 file changed, 8 insertions(+)
> >
> > diff --git a/lib/librte_eal/common/malloc_heap.c
> > b/lib/librte_eal/common/malloc_heap.c
> > index f4e20ea..1607401 100644
> > --- a/lib/librte_eal/common/malloc_heap.c
> > +++ b/lib/librte_eal/common/malloc_heap.c
> > @@ -96,11 +96,19 @@
> > void *start, size_t len)
> > {
> > struct malloc_elem *elem = start;
> > + void *ptr;
> > + size_t data_len
> > +
> >
> > malloc_elem_init(elem, heap, msl, len, elem, len);
> >
> > malloc_elem_insert(elem);
> >
> > + /* Zero out new added memory. */
> > + *ptr = RTE_PTR_ADD(elem, MALLOC_ELEM_HEADER_LEN);
> > + data_len = elem->size - MALLOC_ELEM_OVERHEAD;
> > + memset(ptr, 0, data_len);
> > +
> > elem = malloc_elem_join_adjacent_free(elem);
> >
> > malloc_elem_free_list_insert(elem);
>
> Hi,
>
> The kernel ensures that the newly mapped memory is zeroed,
> and DPDK ensures that files in hugetlbfs are not re-mapped.
> What makes you think that it is not zeroed?
> Were you able to catch [start; start+len) contain non-zero bytes
> at the start of this function?
> If so, is it system memory (not an external heap)?
> If so, what is the CPU, kernel, any custom settings?
>
> Can it be the PMD or the app that uses rte_malloc instead of rte_zmalloc?
>
> This patch cannot be accepted as-is anyway:
> 1. It zeroes memory even if the code was called not via rte_zmalloc().
> 2. It leads to zeroing on both alloc and free, which is suboptimal.
Hi Dmitry, thanks for the review.
In rte_eth_dev_pci_allocate(), imediately after rte_zmalloc_socket()[1]
I printed
the content in gdb. It's not zero.
print ((struct qede_dev *)(eth_dev->data->dev_private))->edev->p_iov_info
cpu: Intel(R) Xeon(R) Gold 5218 CPU @ 2.30GHz
kernel: 4.19.90-2102
[1]
https://github.com/DPDK/dpdk/blob/v20.11/lib/librte_ethdev/rte_ethdev_pci.h#L91-L93
