From: Mitchell Levy <levymitchell0@xxxxxxxxx> Sent: Thursday, August 3, 2023 4:11 PM > > On Wed, Aug 2, 2023 at 10:47 AM Michael Kelley (LINUX) > <mikelley@xxxxxxxxxxxxx> wrote: > > > > From: Mitchell Levy via B4 Relay <devnull+levymitchell0.gmail.com@xxxxxxxxxx> Sent: Tuesday, July 25, 2023 5:24 PM > > > > > > This patch is intended as a proof-of-concept for the new SBRM > > > machinery[1]. For some brief background, the idea behind SBRM is using > > > the __cleanup__ attribute to automatically unlock locks (or otherwise > > > release resources) when they go out of scope, similar to C++ style RAII. > > > This promises some benefits such as making code simpler (particularly > > > where you have lots of goto fail; type constructs) as well as reducing > > > the surface area for certain kinds of bugs. > > > > > > The changes in this patch should not result in any difference in how the > > > code actually runs (i.e., it's purely an exercise in this new syntax > > > sugar). In one instance SBRM was not appropriate, so I left that part > > > alone, but all other locking/unlocking is handled automatically in this > > > patch. > > > > > > Link: https://lore.kernel.org/all/20230626125726.GU4253@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx/ [1] > > > > I haven't previously seen the "[1]" footnote-style identifier used with the > > Link: tag. Usually the "[1]" goes at the beginning of the line with the > > additional information, but that conflicts with the Link: tag. Maybe I'm > > wrong, but you might either omit the footnote-style identifier, or the Link: > > tag, instead of trying to use them together. > > Will be sure to fix this (along with the other formatting issues > raised by you and Boqun) in a v2. > > > > > Separately, have you built a kernel for ARM64 with these changes in > > place? The Hyper-V balloon driver is used on both x86 and ARM64 > > architectures. There's nothing obviously architecture specific here, > > but given that SBRM is new, it might be wise to verify that all is good > > when building and running on ARM64. > > I have built the kernel and confirmed that it's bootable on ARM64. I > also disassembled the hv_balloon.o output by clang and GCC and > compared the result to the disassembly of the pre-patch version. As > far as I can tell, all the changes should be non-functional (some > register renaming and flipping comparison instructions, etc.), but I > don't believe I can thoroughly test at the moment as memory hot-add is > disabled on ARM64. > Excellent. Thanks for indulging me and doing the basic verification on ARM64. You are right about memory hot-add not being used on ARM64. If I recall correctly, only the memory pressure reporting is active on ARM64. Michael
