| Message ID | 20241008184634.245607-5-adhemerval.zanella@linaro.org |
|---|---|
| State | Accepted |
| Commit | f6e849fd7ce2a8954022bd23b94703975b3db0d1 |
| Headers | show |
| Series | Updates for Linux 6.11 | expand |
On Wed, Oct 9, 2024 at 2:47 AM Adhemerval Zanella <adhemerval.zanella@linaro.org> wrote: > > This request the page to be never written out to swap, it will be zeroed > under memory pressure (so kernel can just drop the page), it is inherited > by fork, it is not counted against @code{mlock} budget, and if there is > no enough memory to service a page faults there is no fatal error (so not > signal is sent). > > Tested with build-many-glibcs.py. > --- > manual/llio.texi | 9 +++++++++ > sysdeps/unix/sysv/linux/bits/mman-linux.h | 1 + > sysdeps/unix/sysv/linux/tst-mman-consts.py | 2 +- > 3 files changed, 11 insertions(+), 1 deletion(-) > > diff --git a/manual/llio.texi b/manual/llio.texi > index a035c3e20f..05ab44c6e7 100644 > --- a/manual/llio.texi > +++ b/manual/llio.texi > @@ -1762,6 +1762,15 @@ write dirty metadata out whenever dirty data is written out. Unlike > most other flags, this one will fail unless @code{MAP_SHARED_VALIDATE} > is also given. > > +@item MAP_DROPPABLE > +Request the page to be never written out to swap, it will be zeroed > +under memory pressure (so kernel can just drop the page), it is inherited > +by fork, it is not counted against @code{mlock} budget, and if there is > +not enough memory to service a page fault there is no fatal error (so no > +signal is sent). > + > +The @code{MAP_DROPPABLE} flag is specific to Linux. > + > @end vtable > > @code{mmap} returns the address of the new mapping, or > diff --git a/sysdeps/unix/sysv/linux/bits/mman-linux.h b/sysdeps/unix/sysv/linux/bits/mman-linux.h > index 522333c50a..161a885096 100644 > --- a/sysdeps/unix/sysv/linux/bits/mman-linux.h > +++ b/sysdeps/unix/sysv/linux/bits/mman-linux.h > @@ -43,6 +43,7 @@ > #define MAP_PRIVATE 0x02 /* Changes are private. */ > #define MAP_SHARED_VALIDATE 0x03 /* Share changes and validate > extension flags. */ > +#define MAP_DROPPABLE 0x08 /* Zero memory under memory pressure. */ > #define MAP_TYPE 0x0f /* Mask for type of mapping. */ > > /* Other flags. */ > diff --git a/sysdeps/unix/sysv/linux/tst-mman-consts.py b/sysdeps/unix/sysv/linux/tst-mman-consts.py > index a1137eb1d5..2191bea36f 100644 > --- a/sysdeps/unix/sysv/linux/tst-mman-consts.py > +++ b/sysdeps/unix/sysv/linux/tst-mman-consts.py > @@ -33,7 +33,7 @@ def main(): > help='C compiler (including options) to use') > args = parser.parse_args() > linux_version_headers = glibcsyscalls.linux_kernel_version(args.cc) > - linux_version_glibc = (6, 10) > + linux_version_glibc = (6, 11) > sys.exit(glibcextract.compare_macro_consts( > '#define _GNU_SOURCE 1\n' > '#include <sys/mman.h>\n', > -- > 2.43.0 > We should add a test for it.
On 08/10/24 17:28, H.J. Lu wrote: > On Wed, Oct 9, 2024 at 2:47 AM Adhemerval Zanella > <adhemerval.zanella@linaro.org> wrote: >> >> This request the page to be never written out to swap, it will be zeroed >> under memory pressure (so kernel can just drop the page), it is inherited >> by fork, it is not counted against @code{mlock} budget, and if there is >> no enough memory to service a page faults there is no fatal error (so not >> signal is sent). >> >> Tested with build-many-glibcs.py. >> --- >> manual/llio.texi | 9 +++++++++ >> sysdeps/unix/sysv/linux/bits/mman-linux.h | 1 + >> sysdeps/unix/sysv/linux/tst-mman-consts.py | 2 +- >> 3 files changed, 11 insertions(+), 1 deletion(-) >> >> diff --git a/manual/llio.texi b/manual/llio.texi >> index a035c3e20f..05ab44c6e7 100644 >> --- a/manual/llio.texi >> +++ b/manual/llio.texi >> @@ -1762,6 +1762,15 @@ write dirty metadata out whenever dirty data is written out. Unlike >> most other flags, this one will fail unless @code{MAP_SHARED_VALIDATE} >> is also given. >> >> +@item MAP_DROPPABLE >> +Request the page to be never written out to swap, it will be zeroed >> +under memory pressure (so kernel can just drop the page), it is inherited >> +by fork, it is not counted against @code{mlock} budget, and if there is >> +not enough memory to service a page fault there is no fatal error (so no >> +signal is sent). >> + >> +The @code{MAP_DROPPABLE} flag is specific to Linux. >> + >> @end vtable >> >> @code{mmap} returns the address of the new mapping, or >> diff --git a/sysdeps/unix/sysv/linux/bits/mman-linux.h b/sysdeps/unix/sysv/linux/bits/mman-linux.h >> index 522333c50a..161a885096 100644 >> --- a/sysdeps/unix/sysv/linux/bits/mman-linux.h >> +++ b/sysdeps/unix/sysv/linux/bits/mman-linux.h >> @@ -43,6 +43,7 @@ >> #define MAP_PRIVATE 0x02 /* Changes are private. */ >> #define MAP_SHARED_VALIDATE 0x03 /* Share changes and validate >> extension flags. */ >> +#define MAP_DROPPABLE 0x08 /* Zero memory under memory pressure. */ >> #define MAP_TYPE 0x0f /* Mask for type of mapping. */ >> >> /* Other flags. */ >> diff --git a/sysdeps/unix/sysv/linux/tst-mman-consts.py b/sysdeps/unix/sysv/linux/tst-mman-consts.py >> index a1137eb1d5..2191bea36f 100644 >> --- a/sysdeps/unix/sysv/linux/tst-mman-consts.py >> +++ b/sysdeps/unix/sysv/linux/tst-mman-consts.py >> @@ -33,7 +33,7 @@ def main(): >> help='C compiler (including options) to use') >> args = parser.parse_args() >> linux_version_headers = glibcsyscalls.linux_kernel_version(args.cc) >> - linux_version_glibc = (6, 10) >> + linux_version_glibc = (6, 11) >> sys.exit(glibcextract.compare_macro_consts( >> '#define _GNU_SOURCE 1\n' >> '#include <sys/mman.h>\n', >> -- >> 2.43.0 >> > > We should add a test for it. > I think it would make sense when glibc itself would use this new flag, this patch is just the usual sync one that just update glibc when a kernel release. In any case, we do have a test for [1] where vgetrandom uses it implicitly. [1] https://patchwork.sourceware.org/project/glibc/patch/20240927192310.2504686-1-adhemerval.zanella@linaro.org/
On Wed, Oct 9, 2024, 7:45 PM Adhemerval Zanella Netto < adhemerval.zanella@linaro.org> wrote: > > > On 08/10/24 17:28, H.J. Lu wrote: > > On Wed, Oct 9, 2024 at 2:47 AM Adhemerval Zanella > > <adhemerval.zanella@linaro.org> wrote: > >> > >> This request the page to be never written out to swap, it will be zeroed > >> under memory pressure (so kernel can just drop the page), it is > inherited > >> by fork, it is not counted against @code{mlock} budget, and if there is > >> no enough memory to service a page faults there is no fatal error (so > not > >> signal is sent). > >> > >> Tested with build-many-glibcs.py. > >> --- > >> manual/llio.texi | 9 +++++++++ > >> sysdeps/unix/sysv/linux/bits/mman-linux.h | 1 + > >> sysdeps/unix/sysv/linux/tst-mman-consts.py | 2 +- > >> 3 files changed, 11 insertions(+), 1 deletion(-) > >> > >> diff --git a/manual/llio.texi b/manual/llio.texi > >> index a035c3e20f..05ab44c6e7 100644 > >> --- a/manual/llio.texi > >> +++ b/manual/llio.texi > >> @@ -1762,6 +1762,15 @@ write dirty metadata out whenever dirty data is > written out. Unlike > >> most other flags, this one will fail unless @code{MAP_SHARED_VALIDATE} > >> is also given. > >> > >> +@item MAP_DROPPABLE > >> +Request the page to be never written out to swap, it will be zeroed > >> +under memory pressure (so kernel can just drop the page), it is > inherited > >> +by fork, it is not counted against @code{mlock} budget, and if there is > >> +not enough memory to service a page fault there is no fatal error (so > no > >> +signal is sent). > >> + > >> +The @code{MAP_DROPPABLE} flag is specific to Linux. > >> + > >> @end vtable > >> > >> @code{mmap} returns the address of the new mapping, or > >> diff --git a/sysdeps/unix/sysv/linux/bits/mman-linux.h > b/sysdeps/unix/sysv/linux/bits/mman-linux.h > >> index 522333c50a..161a885096 100644 > >> --- a/sysdeps/unix/sysv/linux/bits/mman-linux.h > >> +++ b/sysdeps/unix/sysv/linux/bits/mman-linux.h > >> @@ -43,6 +43,7 @@ > >> #define MAP_PRIVATE 0x02 /* Changes are private. */ > >> #define MAP_SHARED_VALIDATE 0x03 /* Share changes and validate > >> extension flags. */ > >> +#define MAP_DROPPABLE 0x08 /* Zero memory under memory > pressure. */ > >> #define MAP_TYPE 0x0f /* Mask for type of mapping. */ > >> > >> /* Other flags. */ > >> diff --git a/sysdeps/unix/sysv/linux/tst-mman-consts.py > b/sysdeps/unix/sysv/linux/tst-mman-consts.py > >> index a1137eb1d5..2191bea36f 100644 > >> --- a/sysdeps/unix/sysv/linux/tst-mman-consts.py > >> +++ b/sysdeps/unix/sysv/linux/tst-mman-consts.py > >> @@ -33,7 +33,7 @@ def main(): > >> help='C compiler (including options) to use') > >> args = parser.parse_args() > >> linux_version_headers = glibcsyscalls.linux_kernel_version(args.cc) > >> - linux_version_glibc = (6, 10) > >> + linux_version_glibc = (6, 11) > >> sys.exit(glibcextract.compare_macro_consts( > >> '#define _GNU_SOURCE 1\n' > >> '#include <sys/mman.h>\n', > >> -- > >> 2.43.0 > >> > > > > We should add a test for it. > > > > I think it would make sense when glibc itself would use this new flag, > this patch > is just the usual sync one that just update glibc when a kernel release. mmap is a special case. A test is desirable. > > In any case, we do have a test for [1] where vgetrandom uses it > implicitly. > > [1] > https://patchwork.sourceware.org/project/glibc/patch/20240927192310.2504686-1-adhemerval.zanella@linaro.org/ > > >
On 09/10/24 08:48, H.J. Lu wrote: > > On Wed, Oct 9, 2024, 7:45 PM Adhemerval Zanella Netto <adhemerval.zanella@linaro.org <mailto:adhemerval.zanella@linaro.org>> wrote: > > > > On 08/10/24 17:28, H.J. Lu wrote: > > On Wed, Oct 9, 2024 at 2:47 AM Adhemerval Zanella > > <adhemerval.zanella@linaro.org <mailto:adhemerval.zanella@linaro.org>> wrote: > >> > >> This request the page to be never written out to swap, it will be zeroed > >> under memory pressure (so kernel can just drop the page), it is inherited > >> by fork, it is not counted against @code{mlock} budget, and if there is > >> no enough memory to service a page faults there is no fatal error (so not > >> signal is sent). > >> > >> Tested with build-many-glibcs.py. > >> --- > >> manual/llio.texi | 9 +++++++++ > >> sysdeps/unix/sysv/linux/bits/mman-linux.h | 1 + > >> sysdeps/unix/sysv/linux/tst-mman-consts.py | 2 +- > >> 3 files changed, 11 insertions(+), 1 deletion(-) > >> > >> diff --git a/manual/llio.texi b/manual/llio.texi > >> index a035c3e20f..05ab44c6e7 100644 > >> --- a/manual/llio.texi > >> +++ b/manual/llio.texi > >> @@ -1762,6 +1762,15 @@ write dirty metadata out whenever dirty data is written out. Unlike > >> most other flags, this one will fail unless @code{MAP_SHARED_VALIDATE} > >> is also given. > >> > >> +@item MAP_DROPPABLE > >> +Request the page to be never written out to swap, it will be zeroed > >> +under memory pressure (so kernel can just drop the page), it is inherited > >> +by fork, it is not counted against @code{mlock} budget, and if there is > >> +not enough memory to service a page fault there is no fatal error (so no > >> +signal is sent). > >> + > >> +The @code{MAP_DROPPABLE} flag is specific to Linux. > >> + > >> @end vtable > >> > >> @code{mmap} returns the address of the new mapping, or > >> diff --git a/sysdeps/unix/sysv/linux/bits/mman-linux.h b/sysdeps/unix/sysv/linux/bits/mman-linux.h > >> index 522333c50a..161a885096 100644 > >> --- a/sysdeps/unix/sysv/linux/bits/mman-linux.h > >> +++ b/sysdeps/unix/sysv/linux/bits/mman-linux.h > >> @@ -43,6 +43,7 @@ > >> #define MAP_PRIVATE 0x02 /* Changes are private. */ > >> #define MAP_SHARED_VALIDATE 0x03 /* Share changes and validate > >> extension flags. */ > >> +#define MAP_DROPPABLE 0x08 /* Zero memory under memory pressure. */ > >> #define MAP_TYPE 0x0f /* Mask for type of mapping. */ > >> > >> /* Other flags. */ > >> diff --git a/sysdeps/unix/sysv/linux/tst-mman-consts.py b/sysdeps/unix/sysv/linux/tst-mman-consts.py > >> index a1137eb1d5..2191bea36f 100644 > >> --- a/sysdeps/unix/sysv/linux/tst-mman-consts.py > >> +++ b/sysdeps/unix/sysv/linux/tst-mman-consts.py > >> @@ -33,7 +33,7 @@ def main(): > >> help='C compiler (including options) to use') > >> args = parser.parse_args() > >> linux_version_headers = glibcsyscalls.linux_kernel_version(args.cc) > >> - linux_version_glibc = (6, 10) > >> + linux_version_glibc = (6, 11) > >> sys.exit(glibcextract.compare_macro_consts( > >> '#define _GNU_SOURCE 1\n' > >> '#include <sys/mman.h>\n', > >> -- > >> 2.43.0 > >> > > > > We should add a test for it. > > > > I think it would make sense when glibc itself would use this new flag, this patch > is just the usual sync one that just update glibc when a kernel release. > > > mmap is a special case. A test is desirable. I am not sure if we should do functional kernel testing in this case, and the VM_DROPPABLE test in also tricky because to fully tests requires to apply some system memory pressure (so the page is dropped).
On Wed, Oct 9, 2024 at 9:37 PM Adhemerval Zanella Netto <adhemerval.zanella@linaro.org> wrote: > > > > On 09/10/24 08:48, H.J. Lu wrote: > > > > On Wed, Oct 9, 2024, 7:45 PM Adhemerval Zanella Netto <adhemerval.zanella@linaro.org <mailto:adhemerval.zanella@linaro.org>> wrote: > > > > > > > > On 08/10/24 17:28, H.J. Lu wrote: > > > On Wed, Oct 9, 2024 at 2:47 AM Adhemerval Zanella > > > <adhemerval.zanella@linaro.org <mailto:adhemerval.zanella@linaro.org>> wrote: > > >> > > >> This request the page to be never written out to swap, it will be zeroed > > >> under memory pressure (so kernel can just drop the page), it is inherited > > >> by fork, it is not counted against @code{mlock} budget, and if there is > > >> no enough memory to service a page faults there is no fatal error (so not > > >> signal is sent). > > >> > > >> Tested with build-many-glibcs.py. > > >> --- > > >> manual/llio.texi | 9 +++++++++ > > >> sysdeps/unix/sysv/linux/bits/mman-linux.h | 1 + > > >> sysdeps/unix/sysv/linux/tst-mman-consts.py | 2 +- > > >> 3 files changed, 11 insertions(+), 1 deletion(-) > > >> > > >> diff --git a/manual/llio.texi b/manual/llio.texi > > >> index a035c3e20f..05ab44c6e7 100644 > > >> --- a/manual/llio.texi > > >> +++ b/manual/llio.texi > > >> @@ -1762,6 +1762,15 @@ write dirty metadata out whenever dirty data is written out. Unlike > > >> most other flags, this one will fail unless @code{MAP_SHARED_VALIDATE} > > >> is also given. > > >> > > >> +@item MAP_DROPPABLE > > >> +Request the page to be never written out to swap, it will be zeroed > > >> +under memory pressure (so kernel can just drop the page), it is inherited > > >> +by fork, it is not counted against @code{mlock} budget, and if there is > > >> +not enough memory to service a page fault there is no fatal error (so no > > >> +signal is sent). > > >> + > > >> +The @code{MAP_DROPPABLE} flag is specific to Linux. > > >> + > > >> @end vtable > > >> > > >> @code{mmap} returns the address of the new mapping, or > > >> diff --git a/sysdeps/unix/sysv/linux/bits/mman-linux.h b/sysdeps/unix/sysv/linux/bits/mman-linux.h > > >> index 522333c50a..161a885096 100644 > > >> --- a/sysdeps/unix/sysv/linux/bits/mman-linux.h > > >> +++ b/sysdeps/unix/sysv/linux/bits/mman-linux.h > > >> @@ -43,6 +43,7 @@ > > >> #define MAP_PRIVATE 0x02 /* Changes are private. */ > > >> #define MAP_SHARED_VALIDATE 0x03 /* Share changes and validate > > >> extension flags. */ > > >> +#define MAP_DROPPABLE 0x08 /* Zero memory under memory pressure. */ > > >> #define MAP_TYPE 0x0f /* Mask for type of mapping. */ > > >> > > >> /* Other flags. */ > > >> diff --git a/sysdeps/unix/sysv/linux/tst-mman-consts.py b/sysdeps/unix/sysv/linux/tst-mman-consts.py > > >> index a1137eb1d5..2191bea36f 100644 > > >> --- a/sysdeps/unix/sysv/linux/tst-mman-consts.py > > >> +++ b/sysdeps/unix/sysv/linux/tst-mman-consts.py > > >> @@ -33,7 +33,7 @@ def main(): > > >> help='C compiler (including options) to use') > > >> args = parser.parse_args() > > >> linux_version_headers = glibcsyscalls.linux_kernel_version(args.cc) > > >> - linux_version_glibc = (6, 10) > > >> + linux_version_glibc = (6, 11) > > >> sys.exit(glibcextract.compare_macro_consts( > > >> '#define _GNU_SOURCE 1\n' > > >> '#include <sys/mman.h>\n', > > >> -- > > >> 2.43.0 > > >> > > > > > > We should add a test for it. > > > > > > > I think it would make sense when glibc itself would use this new flag, this patch > > is just the usual sync one that just update glibc when a kernel release. > > > > > > mmap is a special case. A test is desirable. > > I am not sure if we should do functional kernel testing in this case, and the VM_DROPPABLE > test in also tricky because to fully tests requires to apply some system memory pressure > (so the page is dropped). > We have run into the MAP_XXX problem before. We should add a test for each new MAP_XXX. Ther kernel test, tools/testing/selftests/mm/droppable.c, looks reasonable for glibc.
On Thu, Oct 10, 2024 at 5:12 AM H.J. Lu <hjl.tools@gmail.com> wrote: > > On Wed, Oct 9, 2024 at 9:37 PM Adhemerval Zanella Netto > <adhemerval.zanella@linaro.org> wrote: > > > > > > > > On 09/10/24 08:48, H.J. Lu wrote: > > > > > > On Wed, Oct 9, 2024, 7:45 PM Adhemerval Zanella Netto <adhemerval.zanella@linaro.org <mailto:adhemerval.zanella@linaro.org>> wrote: > > > > > > > > > > > > On 08/10/24 17:28, H.J. Lu wrote: > > > > On Wed, Oct 9, 2024 at 2:47 AM Adhemerval Zanella > > > > <adhemerval.zanella@linaro.org <mailto:adhemerval.zanella@linaro.org>> wrote: > > > >> > > > >> This request the page to be never written out to swap, it will be zeroed > > > >> under memory pressure (so kernel can just drop the page), it is inherited > > > >> by fork, it is not counted against @code{mlock} budget, and if there is > > > >> no enough memory to service a page faults there is no fatal error (so not > > > >> signal is sent). > > > >> > > > >> Tested with build-many-glibcs.py. > > > >> --- > > > >> manual/llio.texi | 9 +++++++++ > > > >> sysdeps/unix/sysv/linux/bits/mman-linux.h | 1 + > > > >> sysdeps/unix/sysv/linux/tst-mman-consts.py | 2 +- > > > >> 3 files changed, 11 insertions(+), 1 deletion(-) > > > >> > > > >> diff --git a/manual/llio.texi b/manual/llio.texi > > > >> index a035c3e20f..05ab44c6e7 100644 > > > >> --- a/manual/llio.texi > > > >> +++ b/manual/llio.texi > > > >> @@ -1762,6 +1762,15 @@ write dirty metadata out whenever dirty data is written out. Unlike > > > >> most other flags, this one will fail unless @code{MAP_SHARED_VALIDATE} > > > >> is also given. > > > >> > > > >> +@item MAP_DROPPABLE > > > >> +Request the page to be never written out to swap, it will be zeroed > > > >> +under memory pressure (so kernel can just drop the page), it is inherited > > > >> +by fork, it is not counted against @code{mlock} budget, and if there is > > > >> +not enough memory to service a page fault there is no fatal error (so no > > > >> +signal is sent). > > > >> + > > > >> +The @code{MAP_DROPPABLE} flag is specific to Linux. > > > >> + > > > >> @end vtable > > > >> > > > >> @code{mmap} returns the address of the new mapping, or > > > >> diff --git a/sysdeps/unix/sysv/linux/bits/mman-linux.h b/sysdeps/unix/sysv/linux/bits/mman-linux.h > > > >> index 522333c50a..161a885096 100644 > > > >> --- a/sysdeps/unix/sysv/linux/bits/mman-linux.h > > > >> +++ b/sysdeps/unix/sysv/linux/bits/mman-linux.h > > > >> @@ -43,6 +43,7 @@ > > > >> #define MAP_PRIVATE 0x02 /* Changes are private. */ > > > >> #define MAP_SHARED_VALIDATE 0x03 /* Share changes and validate > > > >> extension flags. */ > > > >> +#define MAP_DROPPABLE 0x08 /* Zero memory under memory pressure. */ > > > >> #define MAP_TYPE 0x0f /* Mask for type of mapping. */ > > > >> > > > >> /* Other flags. */ > > > >> diff --git a/sysdeps/unix/sysv/linux/tst-mman-consts.py b/sysdeps/unix/sysv/linux/tst-mman-consts.py > > > >> index a1137eb1d5..2191bea36f 100644 > > > >> --- a/sysdeps/unix/sysv/linux/tst-mman-consts.py > > > >> +++ b/sysdeps/unix/sysv/linux/tst-mman-consts.py > > > >> @@ -33,7 +33,7 @@ def main(): > > > >> help='C compiler (including options) to use') > > > >> args = parser.parse_args() > > > >> linux_version_headers = glibcsyscalls.linux_kernel_version(args.cc) > > > >> - linux_version_glibc = (6, 10) > > > >> + linux_version_glibc = (6, 11) > > > >> sys.exit(glibcextract.compare_macro_consts( > > > >> '#define _GNU_SOURCE 1\n' > > > >> '#include <sys/mman.h>\n', > > > >> -- > > > >> 2.43.0 > > > >> > > > > > > > > We should add a test for it. > > > > > > > > > > I think it would make sense when glibc itself would use this new flag, this patch > > > is just the usual sync one that just update glibc when a kernel release. > > > > > > > > > mmap is a special case. A test is desirable. > > > > I am not sure if we should do functional kernel testing in this case, and the VM_DROPPABLE > > test in also tricky because to fully tests requires to apply some system memory pressure > > (so the page is dropped). > > > > We have run into the MAP_XXX problem before. We should add a test > for each new MAP_XXX. Ther kernel test, tools/testing/selftests/mm/droppable.c, > looks reasonable for glibc. > Never mind. It was mremap, not mmap.
On Wed, Oct 9, 2024 at 2:47 AM Adhemerval Zanella <adhemerval.zanella@linaro.org> wrote: > > This request the page to be never written out to swap, it will be zeroed > under memory pressure (so kernel can just drop the page), it is inherited > by fork, it is not counted against @code{mlock} budget, and if there is > no enough memory to service a page faults there is no fatal error (so not > signal is sent). > > Tested with build-many-glibcs.py. > --- > manual/llio.texi | 9 +++++++++ > sysdeps/unix/sysv/linux/bits/mman-linux.h | 1 + > sysdeps/unix/sysv/linux/tst-mman-consts.py | 2 +- > 3 files changed, 11 insertions(+), 1 deletion(-) > > diff --git a/manual/llio.texi b/manual/llio.texi > index a035c3e20f..05ab44c6e7 100644 > --- a/manual/llio.texi > +++ b/manual/llio.texi > @@ -1762,6 +1762,15 @@ write dirty metadata out whenever dirty data is written out. Unlike > most other flags, this one will fail unless @code{MAP_SHARED_VALIDATE} > is also given. > > +@item MAP_DROPPABLE > +Request the page to be never written out to swap, it will be zeroed > +under memory pressure (so kernel can just drop the page), it is inherited > +by fork, it is not counted against @code{mlock} budget, and if there is > +not enough memory to service a page fault there is no fatal error (so no > +signal is sent). > + > +The @code{MAP_DROPPABLE} flag is specific to Linux. > + > @end vtable > > @code{mmap} returns the address of the new mapping, or > diff --git a/sysdeps/unix/sysv/linux/bits/mman-linux.h b/sysdeps/unix/sysv/linux/bits/mman-linux.h > index 522333c50a..161a885096 100644 > --- a/sysdeps/unix/sysv/linux/bits/mman-linux.h > +++ b/sysdeps/unix/sysv/linux/bits/mman-linux.h > @@ -43,6 +43,7 @@ > #define MAP_PRIVATE 0x02 /* Changes are private. */ > #define MAP_SHARED_VALIDATE 0x03 /* Share changes and validate > extension flags. */ > +#define MAP_DROPPABLE 0x08 /* Zero memory under memory pressure. */ > #define MAP_TYPE 0x0f /* Mask for type of mapping. */ > > /* Other flags. */ > diff --git a/sysdeps/unix/sysv/linux/tst-mman-consts.py b/sysdeps/unix/sysv/linux/tst-mman-consts.py > index a1137eb1d5..2191bea36f 100644 > --- a/sysdeps/unix/sysv/linux/tst-mman-consts.py > +++ b/sysdeps/unix/sysv/linux/tst-mman-consts.py > @@ -33,7 +33,7 @@ def main(): > help='C compiler (including options) to use') > args = parser.parse_args() > linux_version_headers = glibcsyscalls.linux_kernel_version(args.cc) > - linux_version_glibc = (6, 10) > + linux_version_glibc = (6, 11) > sys.exit(glibcextract.compare_macro_consts( > '#define _GNU_SOURCE 1\n' > '#include <sys/mman.h>\n', > -- > 2.43.0 > LGTM. Reviewed-by: H.J. Lu <hjl.tools@gmail.com> Thanks.
diff --git a/manual/llio.texi b/manual/llio.texi index a035c3e20f..05ab44c6e7 100644 --- a/manual/llio.texi +++ b/manual/llio.texi @@ -1762,6 +1762,15 @@ write dirty metadata out whenever dirty data is written out. Unlike most other flags, this one will fail unless @code{MAP_SHARED_VALIDATE} is also given. +@item MAP_DROPPABLE +Request the page to be never written out to swap, it will be zeroed +under memory pressure (so kernel can just drop the page), it is inherited +by fork, it is not counted against @code{mlock} budget, and if there is +not enough memory to service a page fault there is no fatal error (so no +signal is sent). + +The @code{MAP_DROPPABLE} flag is specific to Linux. + @end vtable @code{mmap} returns the address of the new mapping, or diff --git a/sysdeps/unix/sysv/linux/bits/mman-linux.h b/sysdeps/unix/sysv/linux/bits/mman-linux.h index 522333c50a..161a885096 100644 --- a/sysdeps/unix/sysv/linux/bits/mman-linux.h +++ b/sysdeps/unix/sysv/linux/bits/mman-linux.h @@ -43,6 +43,7 @@ #define MAP_PRIVATE 0x02 /* Changes are private. */ #define MAP_SHARED_VALIDATE 0x03 /* Share changes and validate extension flags. */ +#define MAP_DROPPABLE 0x08 /* Zero memory under memory pressure. */ #define MAP_TYPE 0x0f /* Mask for type of mapping. */ /* Other flags. */ diff --git a/sysdeps/unix/sysv/linux/tst-mman-consts.py b/sysdeps/unix/sysv/linux/tst-mman-consts.py index a1137eb1d5..2191bea36f 100644 --- a/sysdeps/unix/sysv/linux/tst-mman-consts.py +++ b/sysdeps/unix/sysv/linux/tst-mman-consts.py @@ -33,7 +33,7 @@ def main(): help='C compiler (including options) to use') args = parser.parse_args() linux_version_headers = glibcsyscalls.linux_kernel_version(args.cc) - linux_version_glibc = (6, 10) + linux_version_glibc = (6, 11) sys.exit(glibcextract.compare_macro_consts( '#define _GNU_SOURCE 1\n' '#include <sys/mman.h>\n',
This request the page to be never written out to swap, it will be zeroed under memory pressure (so kernel can just drop the page), it is inherited by fork, it is not counted against @code{mlock} budget, and if there is no enough memory to service a page faults there is no fatal error (so not signal is sent). Tested with build-many-glibcs.py. --- manual/llio.texi | 9 +++++++++ sysdeps/unix/sysv/linux/bits/mman-linux.h | 1 + sysdeps/unix/sysv/linux/tst-mman-consts.py | 2 +- 3 files changed, 11 insertions(+), 1 deletion(-)