Since commit 3b8c9f1cdfc50 ("arm64: IPI each CPU after invalidating the I-cache for kernel mappings"), a call to flush_icache_range() will use an IPI to cross-call other online CPUs so that any stale instructions are flushed from their pipelines. This triggers a WARN during the hibernation resume path, where flush_icache_range() is called with interrupts disabled and is therefore prone to deadlock:

| Disabling non-boot CPUs ... | CPU1: shutdown | psci: CPU1 killed. | CPU2: shutdown | psci: CPU2 killed. | CPU3: shutdown | psci: CPU3 killed. | WARNING: CPU: 0 PID: 1 at ../kernel/smp.c:416 smp_call_function_many+0xd4/0x350 | Modules linked in: | CPU: 0 PID: 1 Comm: swapper/0 Not tainted 4.20.0-rc4 #1

Since all secondary CPUs have been taken offline prior to invalidating the I-cache, there's actually no need for an IPI and we can simply call __flush_icache_range() instead.

Cc: stable@vger.kernel.org Fixes: 3b8c9f1cdfc50 ("arm64: IPI each CPU after invalidating the I-cache for kernel mappings") Reported-by: Kunihiko Hayashi hayashi.kunihiko@socionext.com Tested-by: Kunihiko Hayashi hayashi.kunihiko@socionext.com Tested-by: James Morse james.morse@arm.com Signed-off-by: Will Deacon will.deacon@arm.com --- arch/arm64/kernel/hibernate.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/arm64/kernel/hibernate.c b/arch/arm64/kernel/hibernate.c index 6b2686d54411..29cdc99688f3 100644 --- a/arch/arm64/kernel/hibernate.c +++ b/arch/arm64/kernel/hibernate.c @@ -214,7 +214,7 @@ static int create_safe_exec_page(void *src_start, size_t length, }

memcpy((void *)dst, src_start, length); - flush_icache_range(dst, dst + length); + __flush_icache_range(dst, dst + length);

pgdp = pgd_offset_raw(allocator(mask), dst_addr); if (pgd_none(READ_ONCE(*pgdp))) {