David Rientjes <rientjes@xxxxxxxxxx> writes: > On Tue, 12 Jan 2016, Vitaly Kuznetsov wrote: > >> diff --git a/Documentation/memory-hotplug.txt b/Documentation/memory-hotplug.txt >> index ce2cfcf..ceaf40c 100644 >> --- a/Documentation/memory-hotplug.txt >> +++ b/Documentation/memory-hotplug.txt >> @@ -254,12 +254,23 @@ If the memory block is online, you'll read "online". >> If the memory block is offline, you'll read "offline". >> >> >> -5.2. How to online memory >> +5.2. Memory onlining > > Idk why you're changing this title since you didn't change it in the table > of contents and it already pairs with "6.2. How to offline memory". > > This makes it seem like you're covering all memory onlining operations in > the kernel (including xen onlining) rather than just memory onlined by > root. It doesn't cover the fact that xen onlining can be done without > automatic onlining, so I would leave this section's title as it is and > only cover aspects of memory onlining that users are triggering > themselves. Ok, I changed the title to reflect the fact that a special action to online memory is not always required any more but as the global policy stays 'offline' by default for now let's keep the original title. [skip] >> >> + /* online pages if requested */ >> + if (online) >> + online_pages(start >> PAGE_SHIFT, size >> PAGE_SHIFT, >> + MMOP_ONLINE_KEEP); >> + >> goto out; >> >> error: > > Well, shucks, what happens if online_pages() fails, such as if a memory > hot-add notifier returns an errno for MEMORY_GOING_ONLINE? The memory was > added but not subsequently onlined, although auto onlining was set, so how > does userspace know the state it is in? Bad ... we could have checked the return value but I don't see a proper way to handling it here: if we managed to online some blocks we can't revert back. We'll probably have to online pages block-by-block (e.g. by utilizing memory_block_change_state()) handling possible failures. > >> @@ -1315,7 +1327,7 @@ int __ref add_memory(int nid, u64 start, u64 size) >> if (!res) >> return -EEXIST; >> >> - ret = add_memory_resource(nid, res); >> + ret = add_memory_resource(nid, res, memhp_auto_online); >> if (ret < 0) >> release_memory_resource(res); >> return ret; -- Vitaly -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>