On Mon, Jul 15, 2024 at 12:59:45PM -0700, SeongJae Park wrote: > On Mon, 15 Jul 2024 19:12:29 +0200 Greg KH <gregkh@xxxxxxxxxxxxxxxxxxx> wrote: > > > On Mon, Jul 15, 2024 at 09:57:17AM -0700, SeongJae Park wrote: > > > Hi Greg, > > > > > > On Mon, 15 Jul 2024 13:34:48 +0200 <gregkh@xxxxxxxxxxxxxxxxxxx> wrote: > > > > > > > > > > > The patch below does not apply to the 6.1-stable tree. > > > > If someone wants it applied there, or to any other stable or longterm > > > > tree, then please email the backport, including the original git commit > > > > id to <stable@xxxxxxxxxxxxxxx>. > > > > > > > > To reproduce the conflict and resubmit, you may use the following commands: > > > > > > > > git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.1.y > > > > git checkout FETCH_HEAD > > > > git cherry-pick -x 310d6c15e9104c99d5d9d0ff8e5383a79da7d5e6 > > > > > > But this doesn't reproduce the failure on my machine, like below? > > > > > > $ git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.1.y > > > [...] > > > $ git checkout FETCH_HEAD > > > [...] > > > HEAD is now at cac15753b8ce Linux 6.1.99 > > > $ git cherry-pick -x 310d6c15e9104c99d5d9d0ff8e5383a79da7d5e6 > > > Auto-merging mm/damon/core.c > > > [detached HEAD ecd04159c5f3] mm/damon/core: merge regions aggressively when max_nr_regions is unmet > > > Date: Mon Jun 24 10:58:14 2024 -0700 > > > 1 file changed, 19 insertions(+), 2 deletions(-) > > > > Try building it: > > > > DESCEND objtool > > CALL scripts/checksyscalls.sh > > CC mm/damon/core.o > > In file included from ./include/linux/kernel.h:26, > > from ./arch/x86/include/asm/percpu.h:27, > > from ./arch/x86/include/asm/preempt.h:6, > > from ./include/linux/preempt.h:79, > > from ./include/linux/spinlock.h:56, > > from ./include/linux/swait.h:7, > > from ./include/linux/completion.h:12, > > from ./include/linux/damon.h:11, > > from mm/damon/core.c:10: > > mm/damon/core.c: In function \u2018kdamond_merge_regions\u2019: > > ./include/linux/minmax.h:20:35: error: comparison of distinct pointer types lacks a cast [-Werror] > > 20 | (!!(sizeof((typeof(x) *)1 == (typeof(y) *)1))) > > | ^~ > > ./include/linux/minmax.h:26:18: note: in expansion of macro \u2018__typecheck\u2019 > > 26 | (__typecheck(x, y) && __no_side_effects(x, y)) > > | ^~~~~~~~~~~ > > ./include/linux/minmax.h:36:31: note: in expansion of macro \u2018__safe_cmp\u2019 > > 36 | __builtin_choose_expr(__safe_cmp(x, y), \ > > | ^~~~~~~~~~ > > ./include/linux/minmax.h:52:25: note: in expansion of macro \u2018__careful_cmp\u2019 > > 52 | #define max(x, y) __careful_cmp(x, y, >) > > | ^~~~~~~~~~~~~ > > mm/damon/core.c:946:29: note: in expansion of macro \u2018max\u2019 > > 946 | threshold = max(1, threshold * 2); > > | ^~~ > > cc1: all warnings being treated as errors > > make[3]: *** [scripts/Makefile.build:250: mm/damon/core.o] Error 1 > > make[2]: *** [scripts/Makefile.build:503: mm/damon] Error 2 > > make[1]: *** [scripts/Makefile.build:503: mm] Error 2 > > Thank you for sharing this. > > I found the issue can be fixed in two ways. I'd like to know what way you'd > prefer. > > The first way is adding below simple fix to mm/damon/core.c file. > > --- a/mm/damon/core.c > +++ b/mm/damon/core.c > @@ -943,7 +943,7 @@ static void kdamond_merge_regions(struct damon_ctx *c, unsigned int threshold, > damon_merge_regions_of(t, threshold, sz_limit); > nr_regions += damon_nr_regions(t); > } > - threshold = max(1, threshold * 2); > + threshold = max(1U, threshold * 2); > } while (nr_regions > c->attrs.max_nr_regions && > threshold / 2 < max_thres); > } > > The second way is adding upstream commits that avoids the warning of DAMON code > on >=6.6 kernels. Specifically, commit 867046cc7027 ("minmax: relax check to > allow comparison between unsigned arguments and signed constants") is needed. > However, the commit cannot cleanly cherry-picked on its own. Cherry-picking > the commit together with below commits (listed latest one first) made all > commits cleanly be picked and the warning disappears. > > 4ead534fba42 minmax: allow comparisons of 'int' against 'unsigned char/short' > d03eba99f5bf minmax: allow min()/max()/clamp() if the arguments have the same signedness. > 2122e2a4efc2 minmax: clamp more efficiently by avoiding extra comparison > 5efcecd9a3b1 minmax: sanity check constant bounds when clamping I just tried the above, and then added your commit, but I still get the same build error. Did you try it? I would love to get the minmax stuff properly backported to 6.1 (and older if possible), as we have run into this same issue with many changes over the years. > Same warning happens on 5.15.y. In the case, adding the minmax.h upstream > commits only adds more build errors. To remove those, yet another upstream > commit, namely commit a49a64b5bf19 ("tracing: Define the is_signed_type() macro > once") need to be cherry-picked. > > IMHO, the second way is more complex but right for long term, since future > commits for stable tree may also have similar issue. It is not a strong > opinion, and either ways work for me. > > So, Greg, what would you prefer? I would prefer the second way, IF it works. In my limited testing right now, I couldn't get it to work at all. Can you send a series of backported patches that work for you so that I ensure that I'm not just doing something stupid on my end? thanks, greg k-h
