From f91e8d6d76866eafba255864ca617438cec268de Mon Sep 17 00:00:00 2001 From: Michal Hocko Date: Tue, 14 Apr 2015 15:47:11 -0700 Subject: [PATCH] sparc: clarify __GFP_NOFAIL allocation Commit 920c3ed74134 ("[SPARC64]: Add basic infrastructure for MD add/remove notification") has added __GFP_NOFAIL for the allocation request but it hasn't mentioned why is this strict requirement really needed. The code was handling an allocation failure and propagated it properly up the callchain so it is not clear why it is needed. Dave has clarified the intention when I tried to remove the flag as not being necessary: : It is a serious failure. : : If we miss an MDESC update due to this allocation failure, the update : is not an event which gets retransmitted so we will lose the updated : machine description forever. : : We really need this allocation to succeed. So add a comment to clarify the nofail flag and get rid of the failure check because __GFP_NOFAIL allocation doesn't fail. Signed-off-by: Michal Hocko Cc: David Rientjes Cc: Johannes Weiner Cc: Dave Chinner Cc: "Theodore Ts'o" Cc: Mel Gorman Cc: Tetsuo Handa Cc: "David S. Miller" Cc: Vipul Pandya Cc: Jan Kara Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- arch/sparc/kernel/mdesc.c | 22 +++++++++++----------- 1 file changed, 11 insertions(+), 11 deletions(-) diff --git a/arch/sparc/kernel/mdesc.c b/arch/sparc/kernel/mdesc.c index 99632a8..26c80e1 100644 --- a/arch/sparc/kernel/mdesc.c +++ b/arch/sparc/kernel/mdesc.c @@ -130,26 +130,26 @@ static struct mdesc_mem_ops memblock_mdesc_ops = { static struct mdesc_handle *mdesc_kmalloc(unsigned int mdesc_size) { unsigned int handle_size; + struct mdesc_handle *hp; + unsigned long addr; void *base; handle_size = (sizeof(struct mdesc_handle) - sizeof(struct mdesc_hdr) + mdesc_size); + /* + * Allocation has to succeed because mdesc update would be missed + * and such events are not retransmitted. + */ base = kmalloc(handle_size + 15, GFP_KERNEL | __GFP_NOFAIL); - if (base) { - struct mdesc_handle *hp; - unsigned long addr; - - addr = (unsigned long)base; - addr = (addr + 15UL) & ~15UL; - hp = (struct mdesc_handle *) addr; + addr = (unsigned long)base; + addr = (addr + 15UL) & ~15UL; + hp = (struct mdesc_handle *) addr; - mdesc_handle_init(hp, handle_size, base); - return hp; - } + mdesc_handle_init(hp, handle_size, base); - return NULL; + return hp; } static void mdesc_kfree(struct mdesc_handle *hp) -- 2.7.4