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Message-ID: <ab69f5a942824394af6010f75a06c5f7@honor.com> Date: Mon, 22 Dec 2025 09:16:29 +0000 From: yuanlinyu <yuanlinyu@...or.com> To: Enze Li <lienze@...inos.cn>, Huacai Chen <chenhuacai@...nel.org> CC: Alexander Potapenko <glider@...gle.com>, Marco Elver <elver@...gle.com>, Dmitry Vyukov <dvyukov@...gle.com>, Andrew Morton <akpm@...ux-foundation.org>, WANG Xuerui <kernel@...0n.name>, "kasan-dev@...glegroups.com" <kasan-dev@...glegroups.com>, "linux-mm@...ck.org" <linux-mm@...ck.org>, "loongarch@...ts.linux.dev" <loongarch@...ts.linux.dev>, "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>, "enze.li@....com" <enze.li@....com> Subject: RE: [PATCH v2 1/2] LoongArch: kfence: avoid use CONFIG_KFENCE_NUM_OBJECTS > From: Enze Li <lienze@...inos.cn> > Sent: Saturday, December 20, 2025 1:44 PM > To: Huacai Chen <chenhuacai@...nel.org>; yuanlinyu <yuanlinyu@...or.com> > Cc: Alexander Potapenko <glider@...gle.com>; Marco Elver > <elver@...gle.com>; Dmitry Vyukov <dvyukov@...gle.com>; Andrew Morton > <akpm@...ux-foundation.org>; WANG Xuerui <kernel@...0n.name>; > kasan-dev@...glegroups.com; linux-mm@...ck.org; loongarch@...ts.linux.dev; > linux-kernel@...r.kernel.org; enze.li@....com > Subject: Re: [PATCH v2 1/2] LoongArch: kfence: avoid use > CONFIG_KFENCE_NUM_OBJECTS > > On 2025/12/19 10:13, Huacai Chen wrote: > > Hi, Enze, > > > > On Thu, Dec 18, 2025 at 2:39 PM yuan linyu <yuanlinyu@...or.com> wrote: > >> > >> use common kfence macro KFENCE_POOL_SIZE for KFENCE_AREA_SIZE > >> definition > >> > >> Signed-off-by: yuan linyu <yuanlinyu@...or.com> > >> --- > >> arch/loongarch/include/asm/pgtable.h | 3 ++- > >> 1 file changed, 2 insertions(+), 1 deletion(-) > >> > >> diff --git a/arch/loongarch/include/asm/pgtable.h > >> b/arch/loongarch/include/asm/pgtable.h > >> index f41a648a3d9e..e9966c9f844f 100644 > >> --- a/arch/loongarch/include/asm/pgtable.h > >> +++ b/arch/loongarch/include/asm/pgtable.h > >> @@ -10,6 +10,7 @@ > >> #define _ASM_PGTABLE_H > >> > >> #include <linux/compiler.h> > >> +#include <linux/kfence.h> > >> #include <asm/addrspace.h> > >> #include <asm/asm.h> > >> #include <asm/page.h> > >> @@ -96,7 +97,7 @@ extern unsigned long empty_zero_page[PAGE_SIZE / > sizeof(unsigned long)]; > >> #define MODULES_END (MODULES_VADDR + SZ_256M) > >> > >> #ifdef CONFIG_KFENCE > >> -#define KFENCE_AREA_SIZE (((CONFIG_KFENCE_NUM_OBJECTS + 1) > * 2 + 2) * PAGE_SIZE) > >> +#define KFENCE_AREA_SIZE (KFENCE_POOL_SIZE + (2 * > PAGE_SIZE)) > > Can you remember why you didn't use KFENCE_POOL_SIZE at the first place? > > I don't recall the exact reason off the top of my head, but I believe it was due to > complex dependency issues with the header files where KFENCE_POOL_SIZE is > defined. To avoid those complications, we likely opted to use > KFENCE_NUM_OBJECTS directly. > > I checked out the code at commit > (6ad3df56bb199134800933df2afcd7df3b03ef33 "LoongArch: Add KFENCE > (Kernel > Electric-Fence) support") and encountered the following errors when compiling > with this patch applied. > > 8<------------------------------------------------------ > CC arch/loongarch/kernel/asm-offsets.s > In file included from ./arch/loongarch/include/asm/pgtable.h:13, > from ./include/linux/pgtable.h:6, > from ./include/linux/mm.h:29, > from arch/loongarch/kernel/asm-offsets.c:9: > ./include/linux/kfence.h:93:35: warning: 'struct kmem_cache' declared inside > parameter list will n ot be visible outside of this definition or declaration > 93 | void kfence_shutdown_cache(struct kmem_cache *s); > | ^~~~~~~~~~ > ./include/linux/kfence.h:99:29: warning: 'struct kmem_cache' declared inside > parameter list will n ot be visible outside of this definition or declaration > 99 | void *__kfence_alloc(struct kmem_cache *s, size_t size, gfp_t flags); > | ^~~~~~~~~~ > ./include/linux/kfence.h:117:50: warning: 'struct kmem_cache' declared inside > parameter list will not be visible outside of this definition or declaration > 117 | static __always_inline void *kfence_alloc(struct kmem_cache *s, size_t > size, gfp_t flags) > | > ^~~~~~~~~~ > ./include/linux/kfence.h: In function 'kfence_alloc': > ./include/linux/kfence.h:128:31: error: passing argument 1 of '__kfence_alloc' > from incompatible p ointer type [-Wincompatible-pointer-types] > 128 | return __kfence_alloc(s, size, flags); > | ^ > | | > | struct kmem_cache * > ./include/linux/kfence.h:99:41: note: expected 'struct kmem_cache *' but > argument is of type 'stru ct kmem_cache *' > 99 | void *__kfence_alloc(struct kmem_cache *s, size_t size, gfp_t flags); > | ~~~~~~~~~~~~~~~~~~~^ > ------------------------------------------------------>8 > > Similarly, after applying this patch to the latest code > (dd9b004b7ff3289fb7bae35130c0a5c0537266af "Merge tag 'trace-v6.19-rc1'") > from the master branch of the Linux repository and enabling KFENCE, I > encountered the following compilation errors. > > 8<------------------------------------------------------ > CC arch/loongarch/kernel/asm-offsets.s > In file included from ./arch/loongarch/include/asm/pgtable.h:13, > from ./include/linux/pgtable.h:6, > from ./include/linux/mm.h:31, > from arch/loongarch/kernel/asm-offsets.c:11: > ./include/linux/kfence.h:97:35: warning: 'struct kmem_cache' declared inside > parameter list will n ot be visible outside of this definition or declaration > 97 | void kfence_shutdown_cache(struct kmem_cache *s); > | ^~~~~~~~~~ > ./include/linux/kfence.h:103:29: warning: 'struct kmem_cache' declared inside > parameter list will not be visible outside of this definition or declaration > 103 | void *__kfence_alloc(struct kmem_cache *s, size_t size, gfp_t flags); > | ^~~~~~~~~~ > ./include/linux/kfence.h:121:50: warning: 'struct kmem_cache' declared inside > parameter list will not be visible outside of this definition or declaration > 121 | static __always_inline void *kfence_alloc(struct kmem_cache *s, size_t > size, gfp_t flags) > | > ^~~~~~~~~~ > ./include/linux/kfence.h: In function 'kfence_alloc': > ./include/linux/kfence.h:132:31: error: passing argument 1 of '__kfence_alloc' > from incompatible p ointer type [-Wincompatible-pointer-types] > 132 | return __kfence_alloc(s, size, flags); > | ^ > | | > | struct kmem_cache * > ./include/linux/kfence.h:103:41: note: expected 'struct kmem_cache *' > but argument is of type 'str > uct kmem_cache *' > 103 | void *__kfence_alloc(struct kmem_cache *s, size_t size, gfp_t flags); > | ~~~~~~~~~~~~~~~~~~~^ > ------------------------------------------------------>8 > > So, this patch currently runs into compilation issues. linyu probably didn't have > KFENCE enabled when compiling locally, which is why this error was missed. > You can enable it as follows: > > Kernel hacking > Memory Debugging > [*] KFENCE: low-overhead sampling-based memory safety Hi Enze, Sorry only test on arm64. Could you help fix the compile issue and provide a correct change ? Or I need sometime to resolve the issue. > > Thanks, > Enze > > <...>
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