From 70c435ca8dcb64e3d7983a30a14484aa163bb2d2 Mon Sep 17 00:00:00 2001 From: Dave Chinner Date: Tue, 30 Apr 2024 15:28:24 +1000 Subject: [PATCH] stackdepot: use gfp_nested_mask() instead of open coded masking The stackdepot code is used by KASAN and lockdep for recoding stack traces. Both of these track allocation context information, and so their internal allocations must obey the caller allocation contexts to avoid generating their own false positive warnings that have nothing to do with the code they are instrumenting/tracking. We also don't want recording stack traces to deplete emergency memory reserves - debug code is useless if it creates new issues that can't be replicated when the debug code is disabled. Switch the stackdepot allocation masking to use gfp_nested_mask() to address these issues. gfp_nested_mask() also strips GFP_ZONEMASK naturally, so that greatly simplifies this code. Link: https://lkml.kernel.org/r/20240430054604.4169568-3-david@fromorbit.com Signed-off-by: Dave Chinner Reviewed-by: Marco Elver Reviewed-by: Christoph Hellwig Reviewed-by: Vlastimil Babka Reviewed-by: Oscar Salvador Cc: Andrey Konovalov Signed-off-by: Andrew Morton --- lib/stackdepot.c | 11 ++--------- 1 file changed, 2 insertions(+), 9 deletions(-) diff --git a/lib/stackdepot.c b/lib/stackdepot.c index cd8f23455285..5ed34cc963fc 100644 --- a/lib/stackdepot.c +++ b/lib/stackdepot.c @@ -624,15 +624,8 @@ depot_stack_handle_t stack_depot_save_flags(unsigned long *entries, * we won't be able to do that under the lock. */ if (unlikely(can_alloc && !READ_ONCE(new_pool))) { - /* - * Zero out zone modifiers, as we don't have specific zone - * requirements. Keep the flags related to allocation in atomic - * contexts, I/O, nolockdep. - */ - alloc_flags &= ~GFP_ZONEMASK; - alloc_flags &= (GFP_ATOMIC | GFP_KERNEL | __GFP_NOLOCKDEP); - alloc_flags |= __GFP_NOWARN; - page = alloc_pages(alloc_flags, DEPOT_POOL_ORDER); + page = alloc_pages(gfp_nested_mask(alloc_flags), + DEPOT_POOL_ORDER); if (page) prealloc = page_address(page); }