On 17/12/2025 04:18, Yunsheng Lin wrote:
On 2025/12/16 22:26, Kevin Brodsky wrote:
Commit 96ed62ea0298 ("mm: page_frag: fix a compile error when kernel is not compiled") introduced a check to avoid attempting to build the page_frag module if <linux/page_frag_cache.h> is missing.
Unfortunately this check only works if KDIR points to /lib/modules/... or an in-tree kernel build. It always fails if KDIR points to an out-of-tree build (i.e. when the kernel was built with O=$KDIR make) because only generated headers are present under $KDIR/include/ in that case.
<linux/page_frag_cache.h> was added more than a year ago (v6.13) so we can probably live without that check.
As some commercial OS still uses v6.6, I am wondering if we need that
Fair point, I hadn't considered that kselftests are supposed to be buildable against older stable kernels.
check for a little longer, is it possible to do something like below to avoid the flaky check?
@@ -46,7 +46,8 @@ CFLAGS += -U_FORTIFY_SOURCE
KDIR ?= /lib/modules/$(shell uname -r)/build ifneq (,$(wildcard $(KDIR)/Module.symvers)) -ifneq (,$(wildcard $(KDIR)/include/linux/page_frag_cache.h)) +KSRC := $(shell readlink -f $(KDIR)/source 2>/dev/null || echo $(KDIR)) +ifneq (,$(wildcard $(KSRC)/include/linux/page_frag_cache.h)) TEST_GEN_MODS_DIR := page_frag else PAGE_FRAG_WARNING = "missing page_frag_cache.h, please use a newer kernel"
That seems reasonable, and it works for my out-of-tree setup.
Will do that in v2, shall I add your Suggested-by, or maybe Co-developed-by?
- Kevin