From: Eric Dumazet <edumazet@xxxxxxxxxx> Subject: radix-tree: must check __radix_tree_preload() return value __radix_tree_preload() only disables preemption if no error is returned. So we really need to make sure callers always check the return value. idr_preload() contract is to always disable preemption, so we need to add a missing preempt_disable() if an error happened. Similarly, ida_pre_get() only needs to call preempt_enable() in the case no error happened. Link: http://lkml.kernel.org/r/1504637190.15310.62.camel@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx Fixes: 0a835c4f090a ("Reimplement IDR and IDA using the radix tree") Fixes: 7ad3d4d85c7a ("ida: Move ida_bitmap to a percpu variable") Signed-off-by: Eric Dumazet <edumazet@xxxxxxxxxx> Cc: Matthew Wilcox <mawilcox@xxxxxxxxxxxxx> Cc: "Kirill A. Shutemov" <kirill.shutemov@xxxxxxxxxxxxxxx> Cc: <stable@xxxxxxxxxxxxxxx> [4.11+] Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- lib/radix-tree.c | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-) diff -puN lib/radix-tree.c~radix-tree-must-check-__radix_tree_preload-return-value lib/radix-tree.c --- a/lib/radix-tree.c~radix-tree-must-check-__radix_tree_preload-return-value +++ a/lib/radix-tree.c @@ -463,7 +463,7 @@ radix_tree_node_free(struct radix_tree_n * To make use of this facility, the radix tree must be initialised without * __GFP_DIRECT_RECLAIM being passed to INIT_RADIX_TREE(). */ -static int __radix_tree_preload(gfp_t gfp_mask, unsigned nr) +static __must_check int __radix_tree_preload(gfp_t gfp_mask, unsigned nr) { struct radix_tree_preload *rtp; struct radix_tree_node *node; @@ -2104,7 +2104,8 @@ EXPORT_SYMBOL(radix_tree_tagged); */ void idr_preload(gfp_t gfp_mask) { - __radix_tree_preload(gfp_mask, IDR_PRELOAD_SIZE); + if (__radix_tree_preload(gfp_mask, IDR_PRELOAD_SIZE)) + preempt_disable(); } EXPORT_SYMBOL(idr_preload); @@ -2118,13 +2119,13 @@ EXPORT_SYMBOL(idr_preload); */ int ida_pre_get(struct ida *ida, gfp_t gfp) { - __radix_tree_preload(gfp, IDA_PRELOAD_SIZE); /* * The IDA API has no preload_end() equivalent. Instead, * ida_get_new() can return -EAGAIN, prompting the caller * to return to the ida_pre_get() step. */ - preempt_enable(); + if (!__radix_tree_preload(gfp, IDA_PRELOAD_SIZE)) + preempt_enable(); if (!this_cpu_read(ida_bitmap)) { struct ida_bitmap *bitmap = kmalloc(sizeof(*bitmap), gfp); _