On Wed, Feb 12, 2025 at 12:38:23PM -0500, Peter Xu wrote:
> From: Daniil Tatianin <d-tatia...@yandex-team.ru>
>
> This will be used in the following commits to make it possible to only
> lock memory on fault instead of right away.
>
> Signed-off-by: Daniil Tatianin <d-tatia...@yandex-team.ru>
> Reviewed-by: Vladimir Sementsov-Ogievskiy <vsement...@yandex-team.ru>
> Link:
> https://lore.kernel.org/r/20250212143920.1269754-2-d-tatia...@yandex-team.ru
> [peterx: fail os_mlock(on_fault=1) when not supported]
> [peterx: use G_GNUC_UNUSED instead of "(void)on_fault", per Dan]
> Signed-off-by: Peter Xu <pet...@redhat.com>
> ---
> meson.build | 6 ++++++
> include/system/os-posix.h | 2 +-
> include/system/os-win32.h | 2 +-
> migration/postcopy-ram.c | 2 +-
> os-posix.c | 15 +++++++++++++--
> system/vl.c | 2 +-
> 6 files changed, 23 insertions(+), 6 deletions(-)
>
> diff --git a/meson.build b/meson.build
> index 18cf9e2913..59953cbe6b 100644
> --- a/meson.build
> +++ b/meson.build
> @@ -2885,6 +2885,12 @@ config_host_data.set('HAVE_MLOCKALL',
> cc.links(gnu_source_prefix + '''
> return mlockall(MCL_FUTURE);
> }'''))
>
> +config_host_data.set('HAVE_MLOCK_ONFAULT', cc.links(gnu_source_prefix + '''
> + #include <sys/mman.h>
> + int main(void) {
> + return mlockall(MCL_FUTURE | MCL_ONFAULT);
> + }'''))
> +
> have_l2tpv3 = false
> if get_option('l2tpv3').allowed() and have_system
> have_l2tpv3 = cc.has_type('struct mmsghdr',
> diff --git a/include/system/os-posix.h b/include/system/os-posix.h
> index b881ac6c6f..ce5b3bccf8 100644
> --- a/include/system/os-posix.h
> +++ b/include/system/os-posix.h
> @@ -53,7 +53,7 @@ bool os_set_runas(const char *user_id);
> void os_set_chroot(const char *path);
> void os_setup_limits(void);
> void os_setup_post(void);
> -int os_mlock(void);
> +int os_mlock(bool on_fault);
>
> /**
> * qemu_alloc_stack:
> diff --git a/include/system/os-win32.h b/include/system/os-win32.h
> index b82a5d3ad9..bc623061d8 100644
> --- a/include/system/os-win32.h
> +++ b/include/system/os-win32.h
> @@ -123,7 +123,7 @@ static inline bool is_daemonized(void)
> return false;
> }
>
> -static inline int os_mlock(void)
> +static inline int os_mlock(bool on_fault G_GNUC_UNUSED)
So did this actually generate a warning ? We don' even need
G_GNUC_UNUSED unless we're actually seeing warnings about this.
> {
> return -ENOSYS;
> }
> diff --git a/migration/postcopy-ram.c b/migration/postcopy-ram.c
> index 6a6da6ba7f..fc4d8a10df 100644
> --- a/migration/postcopy-ram.c
> +++ b/migration/postcopy-ram.c
> @@ -652,7 +652,7 @@ int postcopy_ram_incoming_cleanup(MigrationIncomingState
> *mis)
> }
>
> if (enable_mlock) {
> - if (os_mlock() < 0) {
> + if (os_mlock(false) < 0) {
> error_report("mlock: %s", strerror(errno));
> /*
> * It doesn't feel right to fail at this point, we have a valid
> diff --git a/os-posix.c b/os-posix.c
> index 9cce55ff2f..52925c23d3 100644
> --- a/os-posix.c
> +++ b/os-posix.c
> @@ -327,18 +327,29 @@ void os_set_line_buffering(void)
> setvbuf(stdout, NULL, _IOLBF, 0);
> }
>
> -int os_mlock(void)
> +int os_mlock(bool on_fault)
> {
> #ifdef HAVE_MLOCKALL
> int ret = 0;
> + int flags = MCL_CURRENT | MCL_FUTURE;
>
> - ret = mlockall(MCL_CURRENT | MCL_FUTURE);
> + if (on_fault) {
> +#ifdef HAVE_MLOCK_ONFAULT
> + flags |= MCL_ONFAULT;
> +#else
> + error_report("mlockall: on_fault not supported");
> + return -EINVAL;
> +#endif
> + }
> +
> + ret = mlockall(flags);
> if (ret < 0) {
> error_report("mlockall: %s", strerror(errno));
> }
>
> return ret;
> #else
> + (void)on_fault;
Still has the pointless (void) cast I mentioned on the previous postign.
> return -ENOSYS;
> #endif
> }
With regards,
Daniel
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