4.9-stable review patch. If anyone has any objections, please let me know.
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From: Nick Desaulniers nick.desaulniers@gmail.com
commit f2f43e566a02a3bdde0a65e6a2e88d707c212a29 upstream.
Clang and its -Wunsequenced emits a warning
mm/vmscan.c:2961:25: error: unsequenced modification and access to 'gfp_mask' [-Wunsequenced] .gfp_mask = (gfp_mask = current_gfp_context(gfp_mask)), ^
While it is not clear to me whether the initialization code violates the specification (6.7.8 par 19 (ISO/IEC 9899) looks like it disagrees) the code is quite confusing and worth cleaning up anyway. Fix this by reusing sc.gfp_mask rather than the updated input gfp_mask parameter.
Link: http://lkml.kernel.org/r/20170510154030.10720-1-nick.desaulniers@gmail.com Signed-off-by: Nick Desaulniers nick.desaulniers@gmail.com Acked-by: Michal Hocko mhocko@suse.com Signed-off-by: Andrew Morton akpm@linux-foundation.org Signed-off-by: Linus Torvalds torvalds@linux-foundation.org [natechancellor: Adjust context due to abscence of 7dea19f9ee63] Signed-off-by: Nathan Chancellor natechancellor@gmail.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- mm/vmscan.c | 13 ++++++------- 1 file changed, 6 insertions(+), 7 deletions(-)
--- a/mm/vmscan.c +++ b/mm/vmscan.c @@ -2966,7 +2966,7 @@ unsigned long try_to_free_pages(struct z unsigned long nr_reclaimed; struct scan_control sc = { .nr_to_reclaim = SWAP_CLUSTER_MAX, - .gfp_mask = (gfp_mask = memalloc_noio_flags(gfp_mask)), + .gfp_mask = memalloc_noio_flags(gfp_mask), .reclaim_idx = gfp_zone(gfp_mask), .order = order, .nodemask = nodemask, @@ -2981,12 +2981,12 @@ unsigned long try_to_free_pages(struct z * 1 is returned so that the page allocator does not OOM kill at this * point. */ - if (throttle_direct_reclaim(gfp_mask, zonelist, nodemask)) + if (throttle_direct_reclaim(sc.gfp_mask, zonelist, nodemask)) return 1;
trace_mm_vmscan_direct_reclaim_begin(order, sc.may_writepage, - gfp_mask, + sc.gfp_mask, sc.reclaim_idx);
nr_reclaimed = do_try_to_free_pages(zonelist, &sc); @@ -3749,16 +3749,15 @@ static int __node_reclaim(struct pglist_ const unsigned long nr_pages = 1 << order; struct task_struct *p = current; struct reclaim_state reclaim_state; - int classzone_idx = gfp_zone(gfp_mask); struct scan_control sc = { .nr_to_reclaim = max(nr_pages, SWAP_CLUSTER_MAX), - .gfp_mask = (gfp_mask = memalloc_noio_flags(gfp_mask)), + .gfp_mask = memalloc_noio_flags(gfp_mask), .order = order, .priority = NODE_RECLAIM_PRIORITY, .may_writepage = !!(node_reclaim_mode & RECLAIM_WRITE), .may_unmap = !!(node_reclaim_mode & RECLAIM_UNMAP), .may_swap = 1, - .reclaim_idx = classzone_idx, + .reclaim_idx = gfp_zone(gfp_mask), };
cond_resched(); @@ -3768,7 +3767,7 @@ static int __node_reclaim(struct pglist_ * and RECLAIM_UNMAP. */ p->flags |= PF_MEMALLOC | PF_SWAPWRITE; - lockdep_set_current_reclaim_state(gfp_mask); + lockdep_set_current_reclaim_state(sc.gfp_mask); reclaim_state.reclaimed_slab = 0; p->reclaim_state = &reclaim_state;