| Message ID | 20231111013928.948838-1-yonghong.song@linux.dev (mailing list archive) |
|---|---|
| State | Accepted |
| Commit | 1fda5bb66ad8fb24ecb3858e61a13a6548428898 |
| Delegated to: | BPF |
| Headers | show |
| Series | [bpf-next,v3] bpf: Do not allocate percpu memory at init stage | expand |
Hi, On 11/11/2023 9:39 AM, Yonghong Song wrote: > Kirill Shutemov reported significant percpu memory consumption increase after > booting in 288-cpu VM ([1]) due to commit 41a5db8d8161 ("bpf: Add support for > non-fix-size percpu mem allocation"). The percpu memory consumption is > increased from 111MB to 969MB. The number is from /proc/meminfo. > > I tried to reproduce the issue with my local VM which at most supports upto > 255 cpus. With 252 cpus, without the above commit, the percpu memory > consumption immediately after boot is 57MB while with the above commit the > percpu memory consumption is 231MB. > > This is not good since so far percpu memory from bpf memory allocator is not > widely used yet. Let us change pre-allocation in init stage to on-demand > allocation when verifier detects there is a need of percpu memory for bpf > program. With this change, percpu memory consumption after boot can be reduced > signicantly. > > [1] https://lore.kernel.org/lkml/20231109154934.4saimljtqx625l3v@box.shutemov.name/ > > Fixes: 41a5db8d8161 ("bpf: Add support for non-fix-size percpu mem allocation") > Reported-and-tested-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> > Signed-off-by: Yonghong Song <yonghong.song@linux.dev> > --- > include/linux/bpf.h | 2 +- > kernel/bpf/core.c | 8 +++----- > kernel/bpf/verifier.c | 20 ++++++++++++++++++-- > 3 files changed, 22 insertions(+), 8 deletions(-) > > Changelog: > v2 -> v3: > - Use dedicated mutex lock (bpf_percpu_ma_lock) > v1 -> v2: > - Add proper Reported-and-tested-by tag. > - Do a check of !bpf_global_percpu_ma_set before acquiring verifier_lock. > > diff --git a/include/linux/bpf.h b/include/linux/bpf.h > index 35bff17396c0..6762dac3ef76 100644 > --- a/include/linux/bpf.h > +++ b/include/linux/bpf.h > @@ -56,7 +56,7 @@ extern struct idr btf_idr; > extern spinlock_t btf_idr_lock; > extern struct kobject *btf_kobj; > extern struct bpf_mem_alloc bpf_global_ma, bpf_global_percpu_ma; > -extern bool bpf_global_ma_set, bpf_global_percpu_ma_set; > +extern bool bpf_global_ma_set; > > typedef u64 (*bpf_callback_t)(u64, u64, u64, u64, u64); > typedef int (*bpf_iter_init_seq_priv_t)(void *private_data, > diff --git a/kernel/bpf/core.c b/kernel/bpf/core.c > index 08626b519ce2..cd3afe57ece3 100644 > --- a/kernel/bpf/core.c > +++ b/kernel/bpf/core.c > @@ -64,8 +64,8 @@ > #define OFF insn->off > #define IMM insn->imm > > -struct bpf_mem_alloc bpf_global_ma, bpf_global_percpu_ma; > -bool bpf_global_ma_set, bpf_global_percpu_ma_set; > +struct bpf_mem_alloc bpf_global_ma; > +bool bpf_global_ma_set; > > /* No hurry in this branch > * > @@ -2934,9 +2934,7 @@ static int __init bpf_global_ma_init(void) > > ret = bpf_mem_alloc_init(&bpf_global_ma, 0, false); > bpf_global_ma_set = !ret; > - ret = bpf_mem_alloc_init(&bpf_global_percpu_ma, 0, true); > - bpf_global_percpu_ma_set = !ret; > - return !bpf_global_ma_set || !bpf_global_percpu_ma_set; > + return ret; > } > late_initcall(bpf_global_ma_init); > #endif > diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c > index a2267d5ed14e..6da370a047fe 100644 > --- a/kernel/bpf/verifier.c > +++ b/kernel/bpf/verifier.c > @@ -26,6 +26,7 @@ > #include <linux/poison.h> > #include <linux/module.h> > #include <linux/cpumask.h> > +#include <linux/bpf_mem_alloc.h> > #include <net/xdp.h> > > #include "disasm.h" > @@ -41,6 +42,9 @@ static const struct bpf_verifier_ops * const bpf_verifier_ops[] = { > #undef BPF_LINK_TYPE > }; > > +struct bpf_mem_alloc bpf_global_percpu_ma; > +static bool bpf_global_percpu_ma_set; > + > /* bpf_check() is a static code analyzer that walks eBPF program > * instruction by instruction and updates register/stack state. > * All paths of conditional branches are analyzed until 'bpf_exit' insn. > @@ -336,6 +340,7 @@ struct bpf_kfunc_call_arg_meta { > struct btf *btf_vmlinux; > > static DEFINE_MUTEX(bpf_verifier_lock); > +static DEFINE_MUTEX(bpf_percpu_ma_lock); > > static const struct bpf_line_info * > find_linfo(const struct bpf_verifier_env *env, u32 insn_off) > @@ -12091,8 +12096,19 @@ static int check_kfunc_call(struct bpf_verifier_env *env, struct bpf_insn *insn, > if (meta.func_id == special_kfunc_list[KF_bpf_obj_new_impl] && !bpf_global_ma_set) > return -ENOMEM; > > - if (meta.func_id == special_kfunc_list[KF_bpf_percpu_obj_new_impl] && !bpf_global_percpu_ma_set) > - return -ENOMEM; > + if (meta.func_id == special_kfunc_list[KF_bpf_percpu_obj_new_impl]) { > + if (!bpf_global_percpu_ma_set) { > + mutex_lock(&bpf_percpu_ma_lock); > + if (!bpf_global_percpu_ma_set) { > + err = bpf_mem_alloc_init(&bpf_global_percpu_ma, 0, true); > + if (!err) > + bpf_global_percpu_ma_set = true; > + } A dumb question here: do we need some memory barrier to guarantee the memory order between bpf_global_percpu_ma_set and bpf_global_percpu_ma ? > + mutex_unlock(&bpf_percpu_ma_lock); > + if (err) > + return err; > + } > + } > > if (((u64)(u32)meta.arg_constant.value) != meta.arg_constant.value) { > verbose(env, "local type ID argument must be in range [0, U32_MAX]\n");
On 11/13/23 4:42 AM, Hou Tao wrote: > Hi, > > On 11/11/2023 9:39 AM, Yonghong Song wrote: >> Kirill Shutemov reported significant percpu memory consumption increase after >> booting in 288-cpu VM ([1]) due to commit 41a5db8d8161 ("bpf: Add support for >> non-fix-size percpu mem allocation"). The percpu memory consumption is >> increased from 111MB to 969MB. The number is from /proc/meminfo. >> >> I tried to reproduce the issue with my local VM which at most supports upto >> 255 cpus. With 252 cpus, without the above commit, the percpu memory >> consumption immediately after boot is 57MB while with the above commit the >> percpu memory consumption is 231MB. >> >> This is not good since so far percpu memory from bpf memory allocator is not >> widely used yet. Let us change pre-allocation in init stage to on-demand >> allocation when verifier detects there is a need of percpu memory for bpf >> program. With this change, percpu memory consumption after boot can be reduced >> signicantly. >> >> [1] https://lore.kernel.org/lkml/20231109154934.4saimljtqx625l3v@box.shutemov.name/ >> >> Fixes: 41a5db8d8161 ("bpf: Add support for non-fix-size percpu mem allocation") >> Reported-and-tested-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> >> Signed-off-by: Yonghong Song <yonghong.song@linux.dev> >> --- >> include/linux/bpf.h | 2 +- >> kernel/bpf/core.c | 8 +++----- >> kernel/bpf/verifier.c | 20 ++++++++++++++++++-- >> 3 files changed, 22 insertions(+), 8 deletions(-) >> >> Changelog: >> v2 -> v3: >> - Use dedicated mutex lock (bpf_percpu_ma_lock) >> v1 -> v2: >> - Add proper Reported-and-tested-by tag. >> - Do a check of !bpf_global_percpu_ma_set before acquiring verifier_lock. >> >> diff --git a/include/linux/bpf.h b/include/linux/bpf.h >> index 35bff17396c0..6762dac3ef76 100644 >> --- a/include/linux/bpf.h >> +++ b/include/linux/bpf.h >> @@ -56,7 +56,7 @@ extern struct idr btf_idr; >> extern spinlock_t btf_idr_lock; >> extern struct kobject *btf_kobj; >> extern struct bpf_mem_alloc bpf_global_ma, bpf_global_percpu_ma; >> -extern bool bpf_global_ma_set, bpf_global_percpu_ma_set; >> +extern bool bpf_global_ma_set; >> >> typedef u64 (*bpf_callback_t)(u64, u64, u64, u64, u64); >> typedef int (*bpf_iter_init_seq_priv_t)(void *private_data, >> diff --git a/kernel/bpf/core.c b/kernel/bpf/core.c >> index 08626b519ce2..cd3afe57ece3 100644 >> --- a/kernel/bpf/core.c >> +++ b/kernel/bpf/core.c >> @@ -64,8 +64,8 @@ >> #define OFF insn->off >> #define IMM insn->imm >> >> -struct bpf_mem_alloc bpf_global_ma, bpf_global_percpu_ma; >> -bool bpf_global_ma_set, bpf_global_percpu_ma_set; >> +struct bpf_mem_alloc bpf_global_ma; >> +bool bpf_global_ma_set; >> >> /* No hurry in this branch >> * >> @@ -2934,9 +2934,7 @@ static int __init bpf_global_ma_init(void) >> >> ret = bpf_mem_alloc_init(&bpf_global_ma, 0, false); >> bpf_global_ma_set = !ret; >> - ret = bpf_mem_alloc_init(&bpf_global_percpu_ma, 0, true); >> - bpf_global_percpu_ma_set = !ret; >> - return !bpf_global_ma_set || !bpf_global_percpu_ma_set; >> + return ret; >> } >> late_initcall(bpf_global_ma_init); >> #endif >> diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c >> index a2267d5ed14e..6da370a047fe 100644 >> --- a/kernel/bpf/verifier.c >> +++ b/kernel/bpf/verifier.c >> @@ -26,6 +26,7 @@ >> #include <linux/poison.h> >> #include <linux/module.h> >> #include <linux/cpumask.h> >> +#include <linux/bpf_mem_alloc.h> >> #include <net/xdp.h> >> >> #include "disasm.h" >> @@ -41,6 +42,9 @@ static const struct bpf_verifier_ops * const bpf_verifier_ops[] = { >> #undef BPF_LINK_TYPE >> }; >> >> +struct bpf_mem_alloc bpf_global_percpu_ma; >> +static bool bpf_global_percpu_ma_set; >> + >> /* bpf_check() is a static code analyzer that walks eBPF program >> * instruction by instruction and updates register/stack state. >> * All paths of conditional branches are analyzed until 'bpf_exit' insn. >> @@ -336,6 +340,7 @@ struct bpf_kfunc_call_arg_meta { >> struct btf *btf_vmlinux; >> >> static DEFINE_MUTEX(bpf_verifier_lock); >> +static DEFINE_MUTEX(bpf_percpu_ma_lock); >> >> static const struct bpf_line_info * >> find_linfo(const struct bpf_verifier_env *env, u32 insn_off) >> @@ -12091,8 +12096,19 @@ static int check_kfunc_call(struct bpf_verifier_env *env, struct bpf_insn *insn, >> if (meta.func_id == special_kfunc_list[KF_bpf_obj_new_impl] && !bpf_global_ma_set) >> return -ENOMEM; >> >> - if (meta.func_id == special_kfunc_list[KF_bpf_percpu_obj_new_impl] && !bpf_global_percpu_ma_set) >> - return -ENOMEM; >> + if (meta.func_id == special_kfunc_list[KF_bpf_percpu_obj_new_impl]) { >> + if (!bpf_global_percpu_ma_set) { >> + mutex_lock(&bpf_percpu_ma_lock); >> + if (!bpf_global_percpu_ma_set) { >> + err = bpf_mem_alloc_init(&bpf_global_percpu_ma, 0, true); >> + if (!err) >> + bpf_global_percpu_ma_set = true; >> + } > A dumb question here: do we need some memory barrier to guarantee the > memory order between bpf_global_percpu_ma_set and bpf_global_percpu_ma ? We should be fine. There is a control dependence on '!err' for 'bpf_global_percpu_ma_set = true'. >> + mutex_unlock(&bpf_percpu_ma_lock); >> + if (err) >> + return err; >> + } >> + } >> >> if (((u64)(u32)meta.arg_constant.value) != meta.arg_constant.value) { >> verbose(env, "local type ID argument must be in range [0, U32_MAX]\n");
On 11/14/2023 11:23 AM, Yonghong Song wrote: > > On 11/13/23 4:42 AM, Hou Tao wrote: >> Hi, >> >> On 11/11/2023 9:39 AM, Yonghong Song wrote: >>> Kirill Shutemov reported significant percpu memory consumption >>> increase after >>> booting in 288-cpu VM ([1]) due to commit 41a5db8d8161 ("bpf: Add >>> support for >>> non-fix-size percpu mem allocation"). The percpu memory consumption is >>> increased from 111MB to 969MB. The number is from /proc/meminfo. >>> >>> I tried to reproduce the issue with my local VM which at most >>> supports upto >>> 255 cpus. With 252 cpus, without the above commit, the percpu memory >>> consumption immediately after boot is 57MB while with the above >>> commit the >>> percpu memory consumption is 231MB. >>> >>> This is not good since so far percpu memory from bpf memory >>> allocator is not >>> widely used yet. Let us change pre-allocation in init stage to >>> on-demand >>> allocation when verifier detects there is a need of percpu memory >>> for bpf >>> program. With this change, percpu memory consumption after boot can >>> be reduced >>> signicantly. >>> >>> [1] >>> https://lore.kernel.org/lkml/20231109154934.4saimljtqx625l3v@box.shutemov.name/ >>> >>> Fixes: 41a5db8d8161 ("bpf: Add support for non-fix-size percpu mem >>> allocation") >>> Reported-and-tested-by: Kirill A. Shutemov >>> <kirill.shutemov@linux.intel.com> >>> Signed-off-by: Yonghong Song <yonghong.song@linux.dev> >>> --- >>> include/linux/bpf.h | 2 +- >>> kernel/bpf/core.c | 8 +++----- >>> kernel/bpf/verifier.c | 20 ++++++++++++++++++-- >>> 3 files changed, 22 insertions(+), 8 deletions(-) >>> >>> Changelog: >>> v2 -> v3: >>> - Use dedicated mutex lock (bpf_percpu_ma_lock) >>> v1 -> v2: >>> - Add proper Reported-and-tested-by tag. >>> - Do a check of !bpf_global_percpu_ma_set before acquiring >>> verifier_lock. >>> >>> diff --git a/include/linux/bpf.h b/include/linux/bpf.h >>> index 35bff17396c0..6762dac3ef76 100644 >>> --- a/include/linux/bpf.h >>> +++ b/include/linux/bpf.h >>> @@ -56,7 +56,7 @@ extern struct idr btf_idr; >>> extern spinlock_t btf_idr_lock; >>> extern struct kobject *btf_kobj; >>> extern struct bpf_mem_alloc bpf_global_ma, bpf_global_percpu_ma; >>> -extern bool bpf_global_ma_set, bpf_global_percpu_ma_set; >>> +extern bool bpf_global_ma_set; >>> typedef u64 (*bpf_callback_t)(u64, u64, u64, u64, u64); >>> typedef int (*bpf_iter_init_seq_priv_t)(void *private_data, >>> diff --git a/kernel/bpf/core.c b/kernel/bpf/core.c >>> index 08626b519ce2..cd3afe57ece3 100644 >>> --- a/kernel/bpf/core.c >>> +++ b/kernel/bpf/core.c >>> @@ -64,8 +64,8 @@ >>> #define OFF insn->off >>> #define IMM insn->imm >>> -struct bpf_mem_alloc bpf_global_ma, bpf_global_percpu_ma; >>> -bool bpf_global_ma_set, bpf_global_percpu_ma_set; >>> +struct bpf_mem_alloc bpf_global_ma; >>> +bool bpf_global_ma_set; >>> /* No hurry in this branch >>> * >>> @@ -2934,9 +2934,7 @@ static int __init bpf_global_ma_init(void) >>> ret = bpf_mem_alloc_init(&bpf_global_ma, 0, false); >>> bpf_global_ma_set = !ret; >>> - ret = bpf_mem_alloc_init(&bpf_global_percpu_ma, 0, true); >>> - bpf_global_percpu_ma_set = !ret; >>> - return !bpf_global_ma_set || !bpf_global_percpu_ma_set; >>> + return ret; >>> } >>> late_initcall(bpf_global_ma_init); >>> #endif >>> diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c >>> index a2267d5ed14e..6da370a047fe 100644 >>> --- a/kernel/bpf/verifier.c >>> +++ b/kernel/bpf/verifier.c >>> @@ -26,6 +26,7 @@ >>> #include <linux/poison.h> >>> #include <linux/module.h> >>> #include <linux/cpumask.h> >>> +#include <linux/bpf_mem_alloc.h> >>> #include <net/xdp.h> >>> #include "disasm.h" >>> @@ -41,6 +42,9 @@ static const struct bpf_verifier_ops * const >>> bpf_verifier_ops[] = { >>> #undef BPF_LINK_TYPE >>> }; >>> +struct bpf_mem_alloc bpf_global_percpu_ma; >>> +static bool bpf_global_percpu_ma_set; >>> + >>> /* bpf_check() is a static code analyzer that walks eBPF program >>> * instruction by instruction and updates register/stack state. >>> * All paths of conditional branches are analyzed until 'bpf_exit' >>> insn. >>> @@ -336,6 +340,7 @@ struct bpf_kfunc_call_arg_meta { >>> struct btf *btf_vmlinux; >>> static DEFINE_MUTEX(bpf_verifier_lock); >>> +static DEFINE_MUTEX(bpf_percpu_ma_lock); >>> static const struct bpf_line_info * >>> find_linfo(const struct bpf_verifier_env *env, u32 insn_off) >>> @@ -12091,8 +12096,19 @@ static int check_kfunc_call(struct >>> bpf_verifier_env *env, struct bpf_insn *insn, >>> if (meta.func_id == >>> special_kfunc_list[KF_bpf_obj_new_impl] && !bpf_global_ma_set) >>> return -ENOMEM; >>> - if (meta.func_id == >>> special_kfunc_list[KF_bpf_percpu_obj_new_impl] && >>> !bpf_global_percpu_ma_set) >>> - return -ENOMEM; >>> + if (meta.func_id == >>> special_kfunc_list[KF_bpf_percpu_obj_new_impl]) { >>> + if (!bpf_global_percpu_ma_set) { >>> + mutex_lock(&bpf_percpu_ma_lock); >>> + if (!bpf_global_percpu_ma_set) { >>> + err = >>> bpf_mem_alloc_init(&bpf_global_percpu_ma, 0, true); >>> + if (!err) >>> + bpf_global_percpu_ma_set = true; >>> + } >> A dumb question here: do we need some memory barrier to guarantee the >> memory order between bpf_global_percpu_ma_set and bpf_global_percpu_ma ? > > We should be fine. There is a control dependence on '!err' for > 'bpf_global_percpu_ma_set = true'. I see. Thanks for the explanation. > >>> + mutex_unlock(&bpf_percpu_ma_lock); >>> + if (err) >>> + return err; >>> + } >>> + } >>> if (((u64)(u32)meta.arg_constant.value) != >>> meta.arg_constant.value) { >>> verbose(env, "local type ID argument must be >>> in range [0, U32_MAX]\n"); > > .
On 11/11/2023 9:39 AM, Yonghong Song wrote: > Kirill Shutemov reported significant percpu memory consumption increase after > booting in 288-cpu VM ([1]) due to commit 41a5db8d8161 ("bpf: Add support for > non-fix-size percpu mem allocation"). The percpu memory consumption is > increased from 111MB to 969MB. The number is from /proc/meminfo. > > I tried to reproduce the issue with my local VM which at most supports upto > 255 cpus. With 252 cpus, without the above commit, the percpu memory > consumption immediately after boot is 57MB while with the above commit the > percpu memory consumption is 231MB. > > This is not good since so far percpu memory from bpf memory allocator is not > widely used yet. Let us change pre-allocation in init stage to on-demand > allocation when verifier detects there is a need of percpu memory for bpf > program. With this change, percpu memory consumption after boot can be reduced > signicantly. > > [1] https://lore.kernel.org/lkml/20231109154934.4saimljtqx625l3v@box.shutemov.name/ > > Fixes: 41a5db8d8161 ("bpf: Add support for non-fix-size percpu mem allocation") > Reported-and-tested-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> > Signed-off-by: Yonghong Song <yonghong.song@linux.dev> Acked-by: Hou Tao <houtao1@huawei.com>
Hello: This patch was applied to bpf/bpf.git (master) by Alexei Starovoitov <ast@kernel.org>: On Fri, 10 Nov 2023 17:39:28 -0800 you wrote: > Kirill Shutemov reported significant percpu memory consumption increase after > booting in 288-cpu VM ([1]) due to commit 41a5db8d8161 ("bpf: Add support for > non-fix-size percpu mem allocation"). The percpu memory consumption is > increased from 111MB to 969MB. The number is from /proc/meminfo. > > I tried to reproduce the issue with my local VM which at most supports upto > 255 cpus. With 252 cpus, without the above commit, the percpu memory > consumption immediately after boot is 57MB while with the above commit the > percpu memory consumption is 231MB. > > [...] Here is the summary with links: - [bpf-next,v3] bpf: Do not allocate percpu memory at init stage https://git.kernel.org/bpf/bpf/c/1fda5bb66ad8 You are awesome, thank you!
diff --git a/include/linux/bpf.h b/include/linux/bpf.h index 35bff17396c0..6762dac3ef76 100644 --- a/include/linux/bpf.h +++ b/include/linux/bpf.h @@ -56,7 +56,7 @@ extern struct idr btf_idr; extern spinlock_t btf_idr_lock; extern struct kobject *btf_kobj; extern struct bpf_mem_alloc bpf_global_ma, bpf_global_percpu_ma; -extern bool bpf_global_ma_set, bpf_global_percpu_ma_set; +extern bool bpf_global_ma_set; typedef u64 (*bpf_callback_t)(u64, u64, u64, u64, u64); typedef int (*bpf_iter_init_seq_priv_t)(void *private_data, diff --git a/kernel/bpf/core.c b/kernel/bpf/core.c index 08626b519ce2..cd3afe57ece3 100644 --- a/kernel/bpf/core.c +++ b/kernel/bpf/core.c @@ -64,8 +64,8 @@ #define OFF insn->off #define IMM insn->imm -struct bpf_mem_alloc bpf_global_ma, bpf_global_percpu_ma; -bool bpf_global_ma_set, bpf_global_percpu_ma_set; +struct bpf_mem_alloc bpf_global_ma; +bool bpf_global_ma_set; /* No hurry in this branch * @@ -2934,9 +2934,7 @@ static int __init bpf_global_ma_init(void) ret = bpf_mem_alloc_init(&bpf_global_ma, 0, false); bpf_global_ma_set = !ret; - ret = bpf_mem_alloc_init(&bpf_global_percpu_ma, 0, true); - bpf_global_percpu_ma_set = !ret; - return !bpf_global_ma_set || !bpf_global_percpu_ma_set; + return ret; } late_initcall(bpf_global_ma_init); #endif diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index a2267d5ed14e..6da370a047fe 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -26,6 +26,7 @@ #include <linux/poison.h> #include <linux/module.h> #include <linux/cpumask.h> +#include <linux/bpf_mem_alloc.h> #include <net/xdp.h> #include "disasm.h" @@ -41,6 +42,9 @@ static const struct bpf_verifier_ops * const bpf_verifier_ops[] = { #undef BPF_LINK_TYPE }; +struct bpf_mem_alloc bpf_global_percpu_ma; +static bool bpf_global_percpu_ma_set; + /* bpf_check() is a static code analyzer that walks eBPF program * instruction by instruction and updates register/stack state. * All paths of conditional branches are analyzed until 'bpf_exit' insn. @@ -336,6 +340,7 @@ struct bpf_kfunc_call_arg_meta { struct btf *btf_vmlinux; static DEFINE_MUTEX(bpf_verifier_lock); +static DEFINE_MUTEX(bpf_percpu_ma_lock); static const struct bpf_line_info * find_linfo(const struct bpf_verifier_env *env, u32 insn_off) @@ -12091,8 +12096,19 @@ static int check_kfunc_call(struct bpf_verifier_env *env, struct bpf_insn *insn, if (meta.func_id == special_kfunc_list[KF_bpf_obj_new_impl] && !bpf_global_ma_set) return -ENOMEM; - if (meta.func_id == special_kfunc_list[KF_bpf_percpu_obj_new_impl] && !bpf_global_percpu_ma_set) - return -ENOMEM; + if (meta.func_id == special_kfunc_list[KF_bpf_percpu_obj_new_impl]) { + if (!bpf_global_percpu_ma_set) { + mutex_lock(&bpf_percpu_ma_lock); + if (!bpf_global_percpu_ma_set) { + err = bpf_mem_alloc_init(&bpf_global_percpu_ma, 0, true); + if (!err) + bpf_global_percpu_ma_set = true; + } + mutex_unlock(&bpf_percpu_ma_lock); + if (err) + return err; + } + } if (((u64)(u32)meta.arg_constant.value) != meta.arg_constant.value) { verbose(env, "local type ID argument must be in range [0, U32_MAX]\n");
Kirill Shutemov reported significant percpu memory consumption increase after booting in 288-cpu VM ([1]) due to commit 41a5db8d8161 ("bpf: Add support for non-fix-size percpu mem allocation"). The percpu memory consumption is increased from 111MB to 969MB. The number is from /proc/meminfo. I tried to reproduce the issue with my local VM which at most supports upto 255 cpus. With 252 cpus, without the above commit, the percpu memory consumption immediately after boot is 57MB while with the above commit the percpu memory consumption is 231MB. This is not good since so far percpu memory from bpf memory allocator is not widely used yet. Let us change pre-allocation in init stage to on-demand allocation when verifier detects there is a need of percpu memory for bpf program. With this change, percpu memory consumption after boot can be reduced signicantly. [1] https://lore.kernel.org/lkml/20231109154934.4saimljtqx625l3v@box.shutemov.name/ Fixes: 41a5db8d8161 ("bpf: Add support for non-fix-size percpu mem allocation") Reported-and-tested-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Signed-off-by: Yonghong Song <yonghong.song@linux.dev> --- include/linux/bpf.h | 2 +- kernel/bpf/core.c | 8 +++----- kernel/bpf/verifier.c | 20 ++++++++++++++++++-- 3 files changed, 22 insertions(+), 8 deletions(-) Changelog: v2 -> v3: - Use dedicated mutex lock (bpf_percpu_ma_lock) v1 -> v2: - Add proper Reported-and-tested-by tag. - Do a check of !bpf_global_percpu_ma_set before acquiring verifier_lock.