| Message ID | bccd2311-79fa-9d88-3c10-067c2438574d@mojatatu.com |
|---|---|
| State | RFC |
| Delegated to: | David Miller |
| Headers | show |
| Series | rcu build on bug | expand |
More clarification - this:
---
diff --git a/net/sched/cls_fw.c b/net/sched/cls_fw.c
index ec945294626a..06510c8c8281 100644
--- a/net/sched/cls_fw.c
+++ b/net/sched/cls_fw.c
@@ -22,12 +22,12 @@
#include <net/pkt_cls.h>
#include <net/sch_generic.h>
-#define HTSIZE 256
+#define HTSIZE 4096
struct fw_head {
+ struct rcu_head rcu;
u32 mask;
struct fw_filter __rcu *ht[HTSIZE];
- struct rcu_head rcu;
};
----
Does not fix it..
cheers,
jamal
On 2020-08-07 11:16 a.m., Jamal Hadi Salim wrote:
>
> Made this small change:
>
> ------
> diff --git a/net/sched/cls_fw.c b/net/sched/cls_fw.c
> index ec945294626a..75d43ed10cd8 100644
> --- a/net/sched/cls_fw.c
> +++ b/net/sched/cls_fw.c
> @@ -22,7 +22,7 @@
> #include <net/pkt_cls.h>
> #include <net/sch_generic.h>
>
> -#define HTSIZE 256
> +#define HTSIZE 4096
>
> struct fw_head {
> u32 mask;
> ---------
>
> Generated compile errors as follows:
>
> ------------
> DESCEND objtool
> CALL scripts/atomic/check-atomics.sh
> CALL scripts/checksyscalls.sh
> CHK include/generated/compile.h
> CC net/sched/cls_fw.o
> In file included from ./include/linux/export.h:43:0,
> from ./include/linux/linkage.h:7,
> from ./include/linux/kernel.h:8,
> from ./include/linux/list.h:9,
> from ./include/linux/module.h:12,
> from net/sched/cls_fw.c:13:
> net/sched/cls_fw.c: In function ‘fw_destroy’:
> ./include/linux/compiler.h:392:38: error: call to
> ‘__compiletime_assert_415’ declared with attribute error: BUILD_BUG_ON
> failed: !__is_kfree_rcu_offset(__builtin_offsetof(typeof(*(head)), rcu))
> _compiletime_assert(condition, msg, __compiletime_assert_, __COUNTER__)
> ^
> ./include/linux/compiler.h:373:4: note: in definition of macro
> ‘__compiletime_assert’
> prefix ## suffix(); \
> ^~~~~~
> ./include/linux/compiler.h:392:2: note: in expansion of macro
> ‘_compiletime_assert’
> _compiletime_assert(condition, msg, __compiletime_assert_, __COUNTER__)
> ^~~~~~~~~~~~~~~~~~~
> ./include/linux/build_bug.h:39:37: note: in expansion of macro
> ‘compiletime_assert’
> #define BUILD_BUG_ON_MSG(cond, msg) compiletime_assert(!(cond), msg)
> ^~~~~~~~~~~~~~~~~~
> ./include/linux/build_bug.h:50:2: note: in expansion of macro
> ‘BUILD_BUG_ON_MSG’
> BUILD_BUG_ON_MSG(condition, "BUILD_BUG_ON failed: " #condition)
> ^~~~~~~~~~~~~~~~
> ./include/linux/rcupdate.h:840:3: note: in expansion of macro
> ‘BUILD_BUG_ON’
> BUILD_BUG_ON(!__is_kfree_rcu_offset(offset)); \
> ^~~~~~~~~~~~
> ./include/linux/rcupdate.h:875:3: note: in expansion of macro ‘__kfree_rcu’
> __kfree_rcu(&((___p)->rhf), offsetof(typeof(*(ptr)), rhf)); \
> ^~~~~~~~~~~
> net/sched/cls_fw.c:151:2: note: in expansion of macro ‘kfree_rcu’
> kfree_rcu(head, rcu);
> ^~~~~~~~~
> scripts/Makefile.build:280: recipe for target 'net/sched/cls_fw.o' failed
> make[2]: *** [net/sched/cls_fw.o] Error 1
> scripts/Makefile.build:497: recipe for target 'net/sched' failed
> make[1]: *** [net/sched] Error 2
> Makefile:1771: recipe for target 'net' failed
> make: *** [net] Error 2
> make: *** Waiting for unfinished jobs....
>
> ----------------
>
> Gets fixed if i reduce the hash buckets of course.
> Looking at include/linux/rcupdate.h I see:
>
> ------
> /*
> * Does the specified offset indicate that the corresponding rcu_head
> * structure can be handled by kfree_rcu()?
> */
> #define __is_kfree_rcu_offset(offset) ((offset) < 4096)
>
> ------
>
> I am guessing the hash table got too large.
> Smells like hard coded expectation?
>
> How to fix?
>
> cheers,
> jamal
On Fri, Aug 7, 2020 at 8:16 AM Jamal Hadi Salim <jhs@mojatatu.com> wrote: > > I am guessing the hash table got too large. > Smells like hard coded expectation? Yeah, that is literally how kfree_rcu() works. > > How to fix? I guess you just have to wrap up kfree() and pass it to call_rcu(). Thanks.
diff --git a/net/sched/cls_fw.c b/net/sched/cls_fw.c index ec945294626a..75d43ed10cd8 100644 --- a/net/sched/cls_fw.c +++ b/net/sched/cls_fw.c @@ -22,7 +22,7 @@ #include <net/pkt_cls.h> #include <net/sch_generic.h> -#define HTSIZE 256 +#define HTSIZE 4096 struct fw_head { u32 mask;
Made this small change: ------ --------- Generated compile errors as follows: ------------ DESCEND objtool CALL scripts/atomic/check-atomics.sh CALL scripts/checksyscalls.sh CHK include/generated/compile.h CC net/sched/cls_fw.o In file included from ./include/linux/export.h:43:0, from ./include/linux/linkage.h:7, from ./include/linux/kernel.h:8, from ./include/linux/list.h:9, from ./include/linux/module.h:12, from net/sched/cls_fw.c:13: net/sched/cls_fw.c: In function ‘fw_destroy’: ./include/linux/compiler.h:392:38: error: call to ‘__compiletime_assert_415’ declared with attribute error: BUILD_BUG_ON failed: !__is_kfree_rcu_offset(__builtin_offsetof(typeof(*(head)), rcu)) _compiletime_assert(condition, msg, __compiletime_assert_, __COUNTER__) ^ ./include/linux/compiler.h:373:4: note: in definition of macro ‘__compiletime_assert’ prefix ## suffix(); \ ^~~~~~ ./include/linux/compiler.h:392:2: note: in expansion of macro ‘_compiletime_assert’ _compiletime_assert(condition, msg, __compiletime_assert_, __COUNTER__) ^~~~~~~~~~~~~~~~~~~ ./include/linux/build_bug.h:39:37: note: in expansion of macro ‘compiletime_assert’ #define BUILD_BUG_ON_MSG(cond, msg) compiletime_assert(!(cond), msg) ^~~~~~~~~~~~~~~~~~ ./include/linux/build_bug.h:50:2: note: in expansion of macro ‘BUILD_BUG_ON_MSG’ BUILD_BUG_ON_MSG(condition, "BUILD_BUG_ON failed: " #condition) ^~~~~~~~~~~~~~~~ ./include/linux/rcupdate.h:840:3: note: in expansion of macro ‘BUILD_BUG_ON’ BUILD_BUG_ON(!__is_kfree_rcu_offset(offset)); \ ^~~~~~~~~~~~ ./include/linux/rcupdate.h:875:3: note: in expansion of macro ‘__kfree_rcu’ __kfree_rcu(&((___p)->rhf), offsetof(typeof(*(ptr)), rhf)); \ ^~~~~~~~~~~ net/sched/cls_fw.c:151:2: note: in expansion of macro ‘kfree_rcu’ kfree_rcu(head, rcu); ^~~~~~~~~ scripts/Makefile.build:280: recipe for target 'net/sched/cls_fw.o' failed make[2]: *** [net/sched/cls_fw.o] Error 1 scripts/Makefile.build:497: recipe for target 'net/sched' failed make[1]: *** [net/sched] Error 2 Makefile:1771: recipe for target 'net' failed make: *** [net] Error 2 make: *** Waiting for unfinished jobs.... ---------------- Gets fixed if i reduce the hash buckets of course. Looking at include/linux/rcupdate.h I see: ------ /* * Does the specified offset indicate that the corresponding rcu_head * structure can be handled by kfree_rcu()? */ #define __is_kfree_rcu_offset(offset) ((offset) < 4096) ------ I am guessing the hash table got too large. Smells like hard coded expectation? How to fix? cheers, jamal