On Fri, Dec 07, 2018 at 12:47:10PM +0000, Will Deacon wrote:
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
Queued for 4.20. Thanks.