On Thu, Feb 20, 2020 at 1:21 PM Minchan Kim <minchan@xxxxxxxxxx> wrote: > > Hi Andrew, > > I submit the fix with inlining here thread but if you prefer submitting > new v7 revision with more inputs, please tell me. > I am happy to resend whole patchset. > > Thanks. > > On Thu, Feb 20, 2020 at 01:15:10PM -0800, Minchan Kim wrote: > > On Fri, Feb 21, 2020 at 03:13:49AM +0800, kbuild test robot wrote: > > > Hi Minchan, > > > > > > I love your patch! Perhaps something to improve: > > > > > > [auto build test WARNING on m68k/for-next] > > > [also build test WARNING on powerpc/next s390/features linus/master v5.6-rc2 next-20200220] > > > [cannot apply to arm64/for-next/core tip/x86/asm arm/for-next hp-parisc/for-next] > > > [if your patch is applied to the wrong git tree, please drop us a note to help > > > improve the system. BTW, we also suggest to use '--base' option to specify the > > > base tree in git format-patch, please see https://stackoverflow.com/a/37406982] > > > > > > url: https://github.com/0day-ci/linux/commits/Minchan-Kim/introduce-memory-hinting-API-for-external-process/20200220-225155 > > > base: https://git.kernel.org/pub/scm/linux/kernel/git/geert/linux-m68k.git for-next > > > config: nds32-randconfig-a001-20200220 (attached as .config) > > > compiler: nds32le-linux-gcc (GCC) 9.2.0 > > > reproduce: > > > wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross > > > chmod +x ~/bin/make.cross > > > # save the attached .config to linux build tree > > > GCC_VERSION=9.2.0 make.cross ARCH=nds32 > > > > > > If you fix the issue, kindly add following tag > > > Reported-by: kbuild test robot <lkp@xxxxxxxxx> > > > > > > All warnings (new ones prefixed by >>): > > > > > > In file included from arch/nds32/include/uapi/asm/unistd.h:10, > > > from arch/nds32/include/asm/unistd.h:6, > > > from arch/nds32/kernel/vdso/sigreturn.S:6: > > > >> include/uapi/asm-generic/unistd.h:858: warning: "__NR_pidfd_getfd" redefined > > > 858 | #define __NR_pidfd_getfd 439 > > > | > > > include/uapi/asm-generic/unistd.h:856: note: this is the location of the previous definition > > > 856 | #define __NR_pidfd_getfd 438 > > > | > > > -- > > > In file included from arch/nds32/include/uapi/asm/unistd.h:10, > > > from arch/nds32/include/asm/unistd.h:6, > > > from <stdin>:2: > > > >> include/uapi/asm-generic/unistd.h:858: warning: "__NR_pidfd_getfd" redefined > > > 858 | #define __NR_pidfd_getfd 439 > > > | > > > include/uapi/asm-generic/unistd.h:856: note: this is the location of the previous definition > > > 856 | #define __NR_pidfd_getfd 438 > > > | > > > <stdin>:1511:2: warning: #warning syscall clone3 not implemented [-Wcpp] > > > >> <stdin>:1520:2: warning: #warning syscall process_madvise not implemented [-Wcpp] > > > -- > > > In file included from arch/nds32/include/uapi/asm/unistd.h:10, > > > from arch/nds32/include/asm/unistd.h:6, > > > from <stdin>:2: > > > >> include/uapi/asm-generic/unistd.h:858: warning: "__NR_pidfd_getfd" redefined > > > 858 | #define __NR_pidfd_getfd 439 > > > | > > > include/uapi/asm-generic/unistd.h:856: note: this is the location of the previous definition > > > 856 | #define __NR_pidfd_getfd 438 > > > | > > > <stdin>:1511:2: warning: #warning syscall clone3 not implemented [-Wcpp] > > > >> <stdin>:1520:2: warning: #warning syscall process_madvise not implemented [-Wcpp] > > > 16 real 2 user 4 sys 39.01% cpu make modules_prepare > > > -- > > > In file included from arch/nds32/include/uapi/asm/unistd.h:10, > > > from arch/nds32/include/asm/unistd.h:6, > > > from <stdin>:2: > > > >> include/uapi/asm-generic/unistd.h:858: warning: "__NR_pidfd_getfd" redefined > > > 858 | #define __NR_pidfd_getfd 439 > > > | > > > include/uapi/asm-generic/unistd.h:856: note: this is the location of the previous definition > > > 856 | #define __NR_pidfd_getfd 438 > > > | > > > <stdin>:1511:2: warning: #warning syscall clone3 not implemented [-Wcpp] > > > >> <stdin>:1520:2: warning: #warning syscall process_madvise not implemented [-Wcpp] > > > In file included from arch/nds32/include/uapi/asm/unistd.h:10, > > > from arch/nds32/include/asm/unistd.h:6, > > > from arch/nds32/kernel/vdso/sigreturn.S:6: > > > >> include/uapi/asm-generic/unistd.h:858: warning: "__NR_pidfd_getfd" redefined > > > 858 | #define __NR_pidfd_getfd 439 > > > | > > > include/uapi/asm-generic/unistd.h:856: note: this is the location of the previous definition > > > 856 | #define __NR_pidfd_getfd 438 > > > | > > > In file included from arch/nds32/include/uapi/asm/unistd.h:10, > > > from arch/nds32/include/asm/unistd.h:6, > > > from arch/nds32/kernel/vdso/gettimeofday.c:11: > > > >> include/uapi/asm-generic/unistd.h:858: warning: "__NR_pidfd_getfd" redefined > > > 858 | #define __NR_pidfd_getfd 439 > > > | > > > include/uapi/asm-generic/unistd.h:856: note: this is the location of the previous definition > > > 856 | #define __NR_pidfd_getfd 438 > > > | > > > 17 real 4 user 6 sys 59.28% cpu make prepare > > > > > > vim +/__NR_pidfd_getfd +858 include/uapi/asm-generic/unistd.h > > > > > > 853 > > > 854 #define __NR_openat2 437 > > > 855 __SYSCALL(__NR_openat2, sys_openat2) > > > 856 #define __NR_pidfd_getfd 438 > > > 857 __SYSCALL(__NR_pidfd_getfd, sys_pidfd_getfd) > > > > 858 #define __NR_pidfd_getfd 439 > > > 859 __SYSCALL(__NR_process_madvise, sys_process_madvise) > > > 860 > > > > > > --- > > > 0-DAY CI Kernel Test Service, Intel Corporation > > > https://lists.01.org/hyperkitty/list/kbuild-all@xxxxxxxxxxxx > > > > > > Hi 0-Day, > > > > Thanks for catching this. Here the fix goes. > > > > From ff74a830277d880716fa0f69c80e9ec9337303d5 Mon Sep 17 00:00:00 2001 > > From: Minchan Kim <minchan@xxxxxxxxxx> > > Date: Fri, 14 Feb 2020 07:42:03 -0800 > > Subject: [PATCH v6 2/8] mm: introduce external memory hinting API > > > > There is usecase that System Management Software(SMS) want to give > > a memory hint like MADV_[COLD|PAGEEOUT] to other processes and > > in the case of Android, it is the ActivityManagerService. > > > > It's similar in spirit to madvise(MADV_WONTNEED), but the information > > required to make the reclaim decision is not known to the app. Instead, > > it is known to the centralized userspace daemon(ActivityManagerService), > > and that daemon must be able to initiate reclaim on its own without > > any app involvement. > > > > To solve the issue, this patch introduces a new syscall process_madvise(2). > > It uses pidfd of an external process to give the hint. > > > > int process_madvise(int pidfd, void *addr, size_t length, int advise, > > unsigned long flag); > > > > Since it could affect other process's address range, only privileged > > process(CAP_SYS_PTRACE) or something else(e.g., being the same UID) > > gives it the right to ptrace the process could use it successfully. > > The flag argument is reserved for future use if we need to extend the > > API. > > > > I think supporting all hints madvise has/will supported/support to > > process_madvise is rather risky. Because we are not sure all hints make > > sense from external process and implementation for the hint may rely on > > the caller being in the current context so it could be error-prone. > > Thus, I just limited hints as MADV_[COLD|PAGEOUT] in this patch. > > > > If someone want to add other hints, we could hear hear the usecase and > > review it for each hint. It's safer for maintenance rather than > > introducing a buggy syscall but hard to fix it later. > > > > Q.1 - Why does any external entity have better knowledge? > > > > Quote from Sandeep > > "For Android, every application (including the special SystemServer) are forked > > from Zygote. The reason of course is to share as many libraries and classes between > > the two as possible to benefit from the preloading during boot. > > > > After applications start, (almost) all of the APIs end up calling into this > > SystemServer process over IPC (binder) and back to the application. > > > > In a fully running system, the SystemServer monitors every single process > > periodically to calculate their PSS / RSS and also decides which process is > > "important" to the user for interactivity. > > > > So, because of how these processes start _and_ the fact that the SystemServer > > is looping to monitor each process, it does tend to *know* which address > > range of the application is not used / useful. > > > > Besides, we can never rely on applications to clean things up themselves. > > We've had the "hey app1, the system is low on memory, please trim your > > memory usage down" notifications for a long time[1]. They rely on > > applications honoring the broadcasts and very few do. > > > > So, if we want to avoid the inevitable killing of the application and > > restarting it, some way to be able to tell the OS about unimportant memory in > > these applications will be useful. > > > > - ssp > > > > Q.2 - How to guarantee the race(i.e., object validation) between when giving a > > hint from an external process and get the hint from the target process? > > > > process_madvise operates on the target process's address space as it exists > > at the instant that process_madvise is called. If the space target process > > can run between the time the process_madvise process inspects the target > > process address space and the time that process_madvise is actually called, > > process_madvise may operate on memory regions that the calling process does > > not expect. It's the responsibility of the process calling process_madvise > > to close this race condition. For example, the calling process can suspend > > the target process with ptrace, SIGSTOP, or the freezer cgroup so that it > > doesn't have an opportunity to change its own address space before > > process_madvise is called. Another option is to operate on memory regions > > that the caller knows a priori will be unchanged in the target process. > > Yet another option is to accept the race for certain process_madvise calls > > after reasoning that mistargeting will do no harm. The suggested API itself > > does not provide synchronization. It also apply other APIs like move_pages, > > process_vm_write. > > > > The race isn't really a problem though. Why is it so wrong to require > > that callers do their own synchronization in some manner? Nobody objects > > to write(2) merely because it's possible for two processes to open the same > > file and clobber each other's writes --- instead, we tell people to use > > flock or something. Think about mmap. It never guarantees newly allocated > > address space is still valid when the user tries to access it because other > > threads could unmap the memory right before. That's where we need > > synchronization by using other API or design from userside. It shouldn't > > be part of API itself. If someone needs more fine-grained synchronization > > rather than process level, there were two ideas suggested - cookie[2] and > > anon-fd[3]. Both are applicable via using last reserved argument of the API > > but I don't think it's necessary right now since we have already ways to > > prevent the race so don't want to add additional complexity with more > > fine-grained optimization model. > > > > To make the API extend, it reserved an unsigned long as last argument > > so we could support it in future if someone really needs it. > > > > Q.3 - Why doesn't ptrace work? > > > > Injecting an madvise in the target process using ptrace would not work for us > > because such injected madvise would have to be executed by the target process, > > which means that process would have to be runnable and that creates the risk > > of the abovementioned race and hinting a wrong VMA. Furthermore, we want to > > act the hint in caller's context, not calle because calle is usually limited > > in cpuset/cgroups or even freezed state so they can't act by themselves > > quick enough, which causes more thrashing/kill. It doesn't work if the > > target process are ptraced(e.g., strace, debugger, minidump) because a > > process can have at most one ptracer. > > > > [1] https://developer.android.com/topic/performance/memory"; > > [2] process_getinfo for getting the cookie which is updated whenever > > vma of process address layout are changed - Daniel Colascione > > - https://lore.kernel.org/lkml/20190520035254.57579-1-minchan@xxxxxxxxxx/T/#m7694416fd179b2066a2c62b5b139b14e3894e224 > > [3] anonymous fd which is used for the object(i.e., address range) > > validation - Michal Hocko > > - https://lore.kernel.org/lkml/20200120112722.GY18451@xxxxxxxxxxxxxx/ > > > > Signed-off-by: Minchan Kim <minchan@xxxxxxxxxx> > > --- > > arch/alpha/kernel/syscalls/syscall.tbl | 1 + > > arch/arm/tools/syscall.tbl | 1 + > > arch/arm64/include/asm/unistd.h | 2 +- > > arch/arm64/include/asm/unistd32.h | 2 + > > arch/ia64/kernel/syscalls/syscall.tbl | 1 + > > arch/m68k/kernel/syscalls/syscall.tbl | 1 + > > arch/microblaze/kernel/syscalls/syscall.tbl | 1 + > > arch/mips/kernel/syscalls/syscall_n32.tbl | 1 + > > arch/mips/kernel/syscalls/syscall_n64.tbl | 1 + > > arch/parisc/kernel/syscalls/syscall.tbl | 1 + > > arch/powerpc/kernel/syscalls/syscall.tbl | 1 + > > arch/s390/kernel/syscalls/syscall.tbl | 1 + > > arch/sh/kernel/syscalls/syscall.tbl | 1 + > > arch/sparc/kernel/syscalls/syscall.tbl | 1 + > > arch/x86/entry/syscalls/syscall_32.tbl | 1 + > > arch/x86/entry/syscalls/syscall_64.tbl | 1 + > > arch/xtensa/kernel/syscalls/syscall.tbl | 1 + > > include/linux/syscalls.h | 2 + > > include/uapi/asm-generic/unistd.h | 4 +- > > kernel/sys_ni.c | 1 + > > mm/madvise.c | 64 +++++++++++++++++++++ > > 21 files changed, 88 insertions(+), 2 deletions(-) > > > > diff --git a/arch/alpha/kernel/syscalls/syscall.tbl b/arch/alpha/kernel/syscalls/syscall.tbl > > index 36d42da7466a..c82952e6fb80 100644 > > --- a/arch/alpha/kernel/syscalls/syscall.tbl > > +++ b/arch/alpha/kernel/syscalls/syscall.tbl > > @@ -477,3 +477,4 @@ > > # 545 reserved for clone3 > > 547 common openat2 sys_openat2 > > 548 common pidfd_getfd sys_pidfd_getfd > > +549 common process_madvise sys_process_madvise > > diff --git a/arch/arm/tools/syscall.tbl b/arch/arm/tools/syscall.tbl > > index 4d1cf74a2caa..54c2719fec46 100644 > > --- a/arch/arm/tools/syscall.tbl > > +++ b/arch/arm/tools/syscall.tbl > > @@ -451,3 +451,4 @@ > > 435 common clone3 sys_clone3 > > 437 common openat2 sys_openat2 > > 438 common pidfd_getfd sys_pidfd_getfd > > +439 common process_madvise sys_process_madvise > > diff --git a/arch/arm64/include/asm/unistd.h b/arch/arm64/include/asm/unistd.h > > index 1dd22da1c3a9..75f04a1023be 100644 > > --- a/arch/arm64/include/asm/unistd.h > > +++ b/arch/arm64/include/asm/unistd.h > > @@ -38,7 +38,7 @@ > > #define __ARM_NR_compat_set_tls (__ARM_NR_COMPAT_BASE + 5) > > #define __ARM_NR_COMPAT_END (__ARM_NR_COMPAT_BASE + 0x800) > > > > -#define __NR_compat_syscalls 439 > > +#define __NR_compat_syscalls 440 > > #endif > > > > #define __ARCH_WANT_SYS_CLONE > > diff --git a/arch/arm64/include/asm/unistd32.h b/arch/arm64/include/asm/unistd32.h > > index c1c61635f89c..2a27be7a1f91 100644 > > --- a/arch/arm64/include/asm/unistd32.h > > +++ b/arch/arm64/include/asm/unistd32.h > > @@ -883,6 +883,8 @@ __SYSCALL(__NR_clone3, sys_clone3) > > __SYSCALL(__NR_openat2, sys_openat2) > > #define __NR_pidfd_getfd 438 > > __SYSCALL(__NR_pidfd_getfd, sys_pidfd_getfd) > > +#define __NR_process_madvise 439 > > +__SYSCALL(__NR_process_madvise, process_madvise) > > > > /* > > * Please add new compat syscalls above this comment and update > > diff --git a/arch/ia64/kernel/syscalls/syscall.tbl b/arch/ia64/kernel/syscalls/syscall.tbl > > index 042911e670b8..9524af1c318c 100644 > > --- a/arch/ia64/kernel/syscalls/syscall.tbl > > +++ b/arch/ia64/kernel/syscalls/syscall.tbl > > @@ -358,3 +358,4 @@ > > # 435 reserved for clone3 > > 437 common openat2 sys_openat2 > > 438 common pidfd_getfd sys_pidfd_getfd > > +439 common process_madvise sys_process_madvise > > diff --git a/arch/m68k/kernel/syscalls/syscall.tbl b/arch/m68k/kernel/syscalls/syscall.tbl > > index f4f49fcb76d0..8197050c097c 100644 > > --- a/arch/m68k/kernel/syscalls/syscall.tbl > > +++ b/arch/m68k/kernel/syscalls/syscall.tbl > > @@ -437,3 +437,4 @@ > > 435 common clone3 __sys_clone3 > > 437 common openat2 sys_openat2 > > 438 common pidfd_getfd sys_pidfd_getfd > > +439 common process_madvise sys_process_madvise > > diff --git a/arch/microblaze/kernel/syscalls/syscall.tbl b/arch/microblaze/kernel/syscalls/syscall.tbl > > index 4c67b11f9c9e..c5b6c8afe445 100644 > > --- a/arch/microblaze/kernel/syscalls/syscall.tbl > > +++ b/arch/microblaze/kernel/syscalls/syscall.tbl > > @@ -443,3 +443,4 @@ > > 435 common clone3 sys_clone3 > > 437 common openat2 sys_openat2 > > 438 common pidfd_getfd sys_pidfd_getfd > > +439 common process_madvise sys_process_madvise > > diff --git a/arch/mips/kernel/syscalls/syscall_n32.tbl b/arch/mips/kernel/syscalls/syscall_n32.tbl > > index 1f9e8ad636cc..8ec8c558aa9c 100644 > > --- a/arch/mips/kernel/syscalls/syscall_n32.tbl > > +++ b/arch/mips/kernel/syscalls/syscall_n32.tbl > > @@ -376,3 +376,4 @@ > > 435 n32 clone3 __sys_clone3 > > 437 n32 openat2 sys_openat2 > > 438 n32 pidfd_getfd sys_pidfd_getfd > > +439 n32 process_madvise sys_process_madvise > > diff --git a/arch/mips/kernel/syscalls/syscall_n64.tbl b/arch/mips/kernel/syscalls/syscall_n64.tbl > > index c0b9d802dbf6..0078f891bb92 100644 > > --- a/arch/mips/kernel/syscalls/syscall_n64.tbl > > +++ b/arch/mips/kernel/syscalls/syscall_n64.tbl > > @@ -352,3 +352,4 @@ > > 435 n64 clone3 __sys_clone3 > > 437 n64 openat2 sys_openat2 > > 438 n64 pidfd_getfd sys_pidfd_getfd > > +439 n64 process_madvise sys_process_madvise > > diff --git a/arch/parisc/kernel/syscalls/syscall.tbl b/arch/parisc/kernel/syscalls/syscall.tbl > > index 52a15f5cd130..09c3b5dc6855 100644 > > --- a/arch/parisc/kernel/syscalls/syscall.tbl > > +++ b/arch/parisc/kernel/syscalls/syscall.tbl > > @@ -435,3 +435,4 @@ > > 435 common clone3 sys_clone3_wrapper > > 437 common openat2 sys_openat2 > > 438 common pidfd_getfd sys_pidfd_getfd > > +439 common process_madvise sys_process_madvise > > diff --git a/arch/powerpc/kernel/syscalls/syscall.tbl b/arch/powerpc/kernel/syscalls/syscall.tbl > > index 35b61bfc1b1a..97eac48c2937 100644 > > --- a/arch/powerpc/kernel/syscalls/syscall.tbl > > +++ b/arch/powerpc/kernel/syscalls/syscall.tbl > > @@ -519,3 +519,4 @@ > > 435 nospu clone3 ppc_clone3 > > 437 common openat2 sys_openat2 > > 438 common pidfd_getfd sys_pidfd_getfd > > +439 common process_madvise sys_process_madvise > > diff --git a/arch/s390/kernel/syscalls/syscall.tbl b/arch/s390/kernel/syscalls/syscall.tbl > > index bd7bd3581a0f..8dc8bfd958ea 100644 > > --- a/arch/s390/kernel/syscalls/syscall.tbl > > +++ b/arch/s390/kernel/syscalls/syscall.tbl > > @@ -440,3 +440,4 @@ > > 435 common clone3 sys_clone3 sys_clone3 > > 437 common openat2 sys_openat2 sys_openat2 > > 438 common pidfd_getfd sys_pidfd_getfd sys_pidfd_getfd > > +439 common process_madvise sys_process_madvise sys_process_madvise > > diff --git a/arch/sh/kernel/syscalls/syscall.tbl b/arch/sh/kernel/syscalls/syscall.tbl > > index c7a30fcd135f..e69d98040777 100644 > > --- a/arch/sh/kernel/syscalls/syscall.tbl > > +++ b/arch/sh/kernel/syscalls/syscall.tbl > > @@ -440,3 +440,4 @@ > > # 435 reserved for clone3 > > 437 common openat2 sys_openat2 > > 438 common pidfd_getfd sys_pidfd_getfd > > +439 common process_madvise sys_process_madvise > > diff --git a/arch/sparc/kernel/syscalls/syscall.tbl b/arch/sparc/kernel/syscalls/syscall.tbl > > index f13615ecdecc..6f6e66dd51f9 100644 > > --- a/arch/sparc/kernel/syscalls/syscall.tbl > > +++ b/arch/sparc/kernel/syscalls/syscall.tbl > > @@ -483,3 +483,4 @@ > > # 435 reserved for clone3 > > 437 common openat2 sys_openat2 > > 438 common pidfd_getfd sys_pidfd_getfd > > +439 common process_madvise sys_process_madvise > > diff --git a/arch/x86/entry/syscalls/syscall_32.tbl b/arch/x86/entry/syscalls/syscall_32.tbl > > index c17cb77eb150..1b2184549e27 100644 > > --- a/arch/x86/entry/syscalls/syscall_32.tbl > > +++ b/arch/x86/entry/syscalls/syscall_32.tbl > > @@ -442,3 +442,4 @@ > > 435 i386 clone3 sys_clone3 __ia32_sys_clone3 > > 437 i386 openat2 sys_openat2 __ia32_sys_openat2 > > 438 i386 pidfd_getfd sys_pidfd_getfd __ia32_sys_pidfd_getfd > > +439 i386 process_madvise sys_process_madvise __ia32_sys_process_madvise > > diff --git a/arch/x86/entry/syscalls/syscall_64.tbl b/arch/x86/entry/syscalls/syscall_64.tbl > > index 44d510bc9b78..82d60eb1e00d 100644 > > --- a/arch/x86/entry/syscalls/syscall_64.tbl > > +++ b/arch/x86/entry/syscalls/syscall_64.tbl > > @@ -359,6 +359,7 @@ > > 435 common clone3 __x64_sys_clone3/ptregs > > 437 common openat2 __x64_sys_openat2 > > 438 common pidfd_getfd __x64_sys_pidfd_getfd > > +439 common process_madvise __x64_sys_process_madvise > > > > # > > # x32-specific system call numbers start at 512 to avoid cache impact > > diff --git a/arch/xtensa/kernel/syscalls/syscall.tbl b/arch/xtensa/kernel/syscalls/syscall.tbl > > index 85a9ab1bc04d..165cae047770 100644 > > --- a/arch/xtensa/kernel/syscalls/syscall.tbl > > +++ b/arch/xtensa/kernel/syscalls/syscall.tbl > > @@ -408,3 +408,4 @@ > > 435 common clone3 sys_clone3 > > 437 common openat2 sys_openat2 > > 438 common pidfd_getfd sys_pidfd_getfd > > +439 common process_madvise sys_process_madvise > > diff --git a/include/linux/syscalls.h b/include/linux/syscalls.h > > index 1815065d52f3..e4cd2c2f8bb4 100644 > > --- a/include/linux/syscalls.h > > +++ b/include/linux/syscalls.h > > @@ -876,6 +876,8 @@ asmlinkage long sys_munlockall(void); > > asmlinkage long sys_mincore(unsigned long start, size_t len, > > unsigned char __user * vec); > > asmlinkage long sys_madvise(unsigned long start, size_t len, int behavior); > > +asmlinkage long sys_process_madvise(int pidfd, unsigned long start, > > + size_t len, int behavior, unsigned long flags); > > asmlinkage long sys_remap_file_pages(unsigned long start, unsigned long size, > > unsigned long prot, unsigned long pgoff, > > unsigned long flags); > > diff --git a/include/uapi/asm-generic/unistd.h b/include/uapi/asm-generic/unistd.h > > index 3a3201e4618e..fa289b91410e 100644 > > --- a/include/uapi/asm-generic/unistd.h > > +++ b/include/uapi/asm-generic/unistd.h > > @@ -855,9 +855,11 @@ __SYSCALL(__NR_clone3, sys_clone3) > > __SYSCALL(__NR_openat2, sys_openat2) > > #define __NR_pidfd_getfd 438 > > __SYSCALL(__NR_pidfd_getfd, sys_pidfd_getfd) > > +#define __NR_process_madvise 439 > > +__SYSCALL(__NR_process_madvise, sys_process_madvise) > > > > #undef __NR_syscalls > > -#define __NR_syscalls 439 > > +#define __NR_syscalls 440 > > > > /* > > * 32 bit systems traditionally used different > > diff --git a/kernel/sys_ni.c b/kernel/sys_ni.c > > index 3b69a560a7ac..6c7332776e8e 100644 > > --- a/kernel/sys_ni.c > > +++ b/kernel/sys_ni.c > > @@ -280,6 +280,7 @@ COND_SYSCALL(mlockall); > > COND_SYSCALL(munlockall); > > COND_SYSCALL(mincore); > > COND_SYSCALL(madvise); > > +COND_SYSCALL(process_madvise); > > COND_SYSCALL(remap_file_pages); > > COND_SYSCALL(mbind); > > COND_SYSCALL_COMPAT(mbind); > > diff --git a/mm/madvise.c b/mm/madvise.c > > index f75c86b6c463..f29155b8185d 100644 > > --- a/mm/madvise.c > > +++ b/mm/madvise.c > > @@ -17,6 +17,7 @@ > > #include <linux/falloc.h> > > #include <linux/fadvise.h> > > #include <linux/sched.h> > > +#include <linux/sched/mm.h> > > #include <linux/ksm.h> > > #include <linux/fs.h> > > #include <linux/file.h> > > @@ -986,6 +987,18 @@ madvise_behavior_valid(int behavior) > > } > > } > > > > +static bool > > +process_madvise_behavior_valid(int behavior) > > +{ > > + switch (behavior) { > > + case MADV_COLD: > > + case MADV_PAGEOUT: > > + return true; > > + default: > > + return false; > > + } > > +} > > + > > /*/ > > * The madvise(2) system call. > > * > > @@ -1033,6 +1046,11 @@ madvise_behavior_valid(int behavior) > > * MADV_DONTDUMP - the application wants to prevent pages in the given range > > * from being included in its core dump. > > * MADV_DODUMP - cancel MADV_DONTDUMP: no longer exclude from core dump. > > + * MADV_COLD - the application uses the memory less so the kernel can "kernel can" implies that kernel might not deactivate the pages, which IIUC is not the case. Maybe rephrase as "MADV_COLD - the application is not expected to use this memory soon, deactivate pages in this range so that they can be reclaimed easily if memory pressure happens."" > > + * deactivate the memory to evict them quickly when the memory > > + * pressure happen. > > + * MADV_PAGEOUT - the application uses the memroy very rarely so kernel can s/memroy/memory > > + * page out the memory instantly. same nit about the usage of "kernel can". Maybe rephrase as "MADV_PAGEOUT - the application is not expected to use this memory soon, page out the pages in this range immediately."" > > * > > * return values: > > * zero - success > > @@ -1150,3 +1168,49 @@ SYSCALL_DEFINE3(madvise, unsigned long, start, size_t, len_in, int, behavior) > > { > > return do_madvise(current, current->mm, start, len_in, behavior); > > } > > + > > +SYSCALL_DEFINE5(process_madvise, int, pidfd, unsigned long, start, > > + size_t, len_in, int, behavior, unsigned long, flags) > > +{ > > + int ret; > > + struct fd f; > > + struct pid *pid; > > + struct task_struct *task; > > + struct mm_struct *mm; > > + > > + if (flags != 0) > > + return -EINVAL; > > + > > + if (!process_madvise_behavior_valid(behavior)) > > + return -EINVAL; > > + > > + f = fdget(pidfd); > > + if (!f.file) > > + return -EBADF; > > + > > + pid = pidfd_pid(f.file); > > + if (IS_ERR(pid)) { > > + ret = PTR_ERR(pid); > > + goto fdput; > > + } > > + > > + task = get_pid_task(pid, PIDTYPE_PID); > > + if (!task) { > > + ret = -ESRCH; > > + goto fdput; > > + } > > + > > + mm = mm_access(task, PTRACE_MODE_ATTACH_FSCREDS); > > + if (IS_ERR_OR_NULL(mm)) { > > + ret = IS_ERR(mm) ? PTR_ERR(mm) : -ESRCH; > > + goto release_task; > > + } > > + > > + ret = do_madvise(task, mm, start, len_in, behavior); > > + mmput(mm); > > +release_task: > > + put_task_struct(task); > > +fdput: > > + fdput(f); > > + return ret; > > +} > > -- > > 2.25.0.265.gbab2e86ba0-goog > > > Reviewed-by: Suren Baghdasaryan <surenb@xxxxxxxxxx>
