On 25/09/2018 14:15, Balbir Singh wrote: > On Tue, Sep 25, 2018 at 11:14:56AM +0200, David Hildenbrand wrote: >> Let's perform all checking + offlining + removing under >> device_hotplug_lock, so nobody can mess with these devices via >> sysfs concurrently. >> >> Cc: Benjamin Herrenschmidt <[email protected]> >> Cc: Paul Mackerras <[email protected]> >> Cc: Michael Ellerman <[email protected]> >> Cc: Rashmica Gupta <[email protected]> >> Cc: Balbir Singh <[email protected]> >> Cc: Michael Neuling <[email protected]> >> Reviewed-by: Pavel Tatashin <[email protected]> >> Reviewed-by: Rashmica Gupta <[email protected]> >> Signed-off-by: David Hildenbrand <[email protected]> >> --- >> arch/powerpc/platforms/powernv/memtrace.c | 4 +++- >> 1 file changed, 3 insertions(+), 1 deletion(-) >> >> diff --git a/arch/powerpc/platforms/powernv/memtrace.c >> b/arch/powerpc/platforms/powernv/memtrace.c >> index fdd48f1a39f7..d84d09c56af9 100644 >> --- a/arch/powerpc/platforms/powernv/memtrace.c >> +++ b/arch/powerpc/platforms/powernv/memtrace.c >> @@ -70,6 +70,7 @@ static int change_memblock_state(struct memory_block *mem, >> void *arg) >> return 0; >> } >> >> +/* called with device_hotplug_lock held */ >> static bool memtrace_offline_pages(u32 nid, u64 start_pfn, u64 nr_pages) >> { >> u64 end_pfn = start_pfn + nr_pages - 1; >> @@ -111,6 +112,7 @@ static u64 memtrace_alloc_node(u32 nid, u64 size) >> end_pfn = round_down(end_pfn - nr_pages, nr_pages); >> >> for (base_pfn = end_pfn; base_pfn > start_pfn; base_pfn -= nr_pages) { >> + lock_device_hotplug(); > > Why not grab the lock before the for loop? That way we can avoid bad cases > like a > large node being scanned for a small number of pages (nr_pages). Ideally we > need > a cond_resched() in the loop, but I guess offline_pages() has one.
Yes, it does. I can move it out of the loop, thanks! > > Acked-by: Balbir Singh <[email protected]> > -- Thanks, David / dhildenb _______________________________________________ devel mailing list [email protected] http://driverdev.linuxdriverproject.org/mailman/listinfo/driverdev-devel
