The flag update_cur_sg tracks whether contiguous pages
from a new set of page_list pages can be merged into the
SGE passed into ib_umem_add_sg_table(). If this flag is true,
but the total segment length exceeds the max_seg_size supported
by HW, we avoid combining to this SGE and move to a new SGE (x)
and merge 'len' pages to it. However, if i < npages, the next
iteration can incorrectly merge 'len' contiguous pages into x
instead of into a new SGE since update_cur_sg is still true.
Reset update_cur_sg to false always after the check to merge
pages into the first SGE passed in to ib_umem_add_sg_table().
Also, prevent a new SGE's segment length from ever exceeding
HW max_seg_sz.
There is a crash on hfi1 as result of this where-in max_seg_sz is
defaulting to 64K. Due to above bug, unfolding SGE's in __ib_umem_release
points to a bad page ptr.
[ 6146.398661] TEST comp-wfr.perfnative.STL-22166-WDT _ perftest native 2-Write_4097QP_4MB STARTING at 1555387093
[ 6893.954261] BUG: Bad page state in process ib_write_bw pfn:7ebca0
[ 6893.961996] page:ffffcd675faf2800 count:0 mapcount:1 mapping:0000000000000000 index:0x1
[ 6893.971565] flags: 0x17ffffc0000000()
[ 6893.976257] raw: 0017ffffc0000000 dead000000000100 dead000000000200 0000000000000000
[ 6893.985518] raw: 0000000000000001 0000000000000000 0000000000000000 0000000000000000
[ 6893.994768] page dumped because: nonzero mapcount
[ 6894.084904] CPU: 18 PID: 15853 Comm: ib_write_bw Tainted: G B 5.1.0-rc4 #1
[ 6894.094644] Hardware name: Intel Corporation S2600CWR/S2600CW, BIOS SE5C610.86B.01.01.0014.121820151719 12/18/2015
[ 6894.106816] Call Trace:
[ 6894.110155] dump_stack+0x5a/0x73
[ 6894.114447] bad_page+0xf5/0x10f
[ 6894.118640] free_pcppages_bulk+0x62c/0x680
[ 6894.123904] free_unref_page+0x54/0x70
[ 6894.128692] __ib_umem_release+0x148/0x1a0 [ib_uverbs]
[ 6894.135028] ib_umem_release+0x22/0x80 [ib_uverbs]
[ 6894.141003] rvt_dereg_mr+0x67/0xb0 [rdmavt]
[ 6894.146382] ib_dereg_mr_user+0x37/0x60 [ib_core]
[ 6894.152235] destroy_hw_idr_uobject+0x1c/0x50 [ib_uverbs]
[ 6894.158868] uverbs_destroy_uobject+0x2e/0x180 [ib_uverbs]
[ 6894.165611] uobj_destroy+0x4d/0x60 [ib_uverbs]
[ 6894.171277] __uobj_get_destroy+0x33/0x50 [ib_uverbs]
[ 6894.177547] __uobj_perform_destroy+0xa/0x30 [ib_uverbs]
[ 6894.184094] ib_uverbs_dereg_mr+0x66/0x90 [ib_uverbs]
[ 6894.190337] ib_uverbs_write+0x3e1/0x500 [ib_uverbs]
[ 6894.196473] vfs_write+0xad/0x1b0
[ 6894.200762] ksys_write+0x5a/0xd0
[ 6894.205069] do_syscall_64+0x5b/0x180
[ 6894.209728] entry_SYSCALL_64_after_hwframe+0x44/0xa9
Fixes: d10bcf947a3e ("RDMA/umem: Combine contiguous PAGE_SIZE regions in SGEs")
Cc: Dennis Dalessandro <dennis.dalessandro@xxxxxxxxx>
Tested-by: Mike Marciniszyn <mike.marciniszyn@xxxxxxxxx>
Reviewed-by: Michael J. Ruhl <michael.j.ruhl@xxxxxxxxx>
Signed-off-by: Shiraz Saleem <shiraz.saleem@xxxxxxxxx>
---
drivers/infiniband/core/umem.c | 15 +++++++++------
1 file changed, 9 insertions(+), 6 deletions(-)
diff --git a/drivers/infiniband/core/umem.c b/drivers/infiniband/core/umem.c
index 7e912a9..04795c5 100644
--- a/drivers/infiniband/core/umem.c
+++ b/drivers/infiniband/core/umem.c
@@ -101,17 +101,20 @@ static struct scatterlist *ib_umem_add_sg_table(struct scatterlist *sg,
* at i
*/
for (len = 0; i != npages &&
- first_pfn + len == page_to_pfn(page_list[i]);
+ first_pfn + len == page_to_pfn(page_list[i]) &&
+ len < (max_seg_sz >> PAGE_SHIFT);
len++)
i++;
/* Squash N contiguous pages from page_list into current sge */
- if (update_cur_sg &&
- ((max_seg_sz - sg->length) >= (len << PAGE_SHIFT))) {
- sg_set_page(sg, sg_page(sg),
- sg->length + (len << PAGE_SHIFT), 0);
+ if (update_cur_sg) {
+ if ((max_seg_sz - sg->length) >= (len << PAGE_SHIFT)) {
+ sg_set_page(sg, sg_page(sg),
+ sg->length + (len << PAGE_SHIFT), 0);
+ update_cur_sg = false;
+ continue;
+ }
update_cur_sg = false;
- continue;
}
/* Squash N contiguous pages into next sge or first sge */
--
1.8.3.1
