| Message ID | 20190130233605.22163-3-muriloo@linux.ibm.com |
|---|---|
| State | New |
| Headers | show |
| Series | mmap-alloc: fix hugetlbfs misaligned length in ppc64 | expand |
On Wed, 30 Jan 2019 21:36:05 -0200 Murilo Opsfelder Araujo <muriloo@linux.ibm.com> wrote: > The commit 7197fb4058bcb68986bae2bb2c04d6370f3e7218 ("util/mmap-alloc: > fix hugetlb support on ppc64") fixed Huge TLB mappings on ppc64. > > However, we still need to consider the underlying huge page size > during munmap() because it requires that both address and length be a > multiple of the underlying huge page size for Huge TLB mappings. > Quote from "Huge page (Huge TLB) mappings" paragraph under NOTES > section of the munmap(2) manual: > > "For munmap(), addr and length must both be a multiple of the > underlying huge page size." > > On ppc64, the munmap() in qemu_ram_munmap() does not work for Huge TLB > mappings because the mapped segment can be aligned with the underlying > huge page size, not aligned with the native system page size, as > returned by getpagesize(). > > This has the side effect of not releasing huge pages back to the pool > after a hugetlbfs file-backed memory device is hot-unplugged. > > This patch fixes the situation in qemu_ram_mmap() and > qemu_ram_munmap() by considering the underlying page size on ppc64. > > After this patch, memory hot-unplug releases huge pages back to the > pool. > > Fixes: 7197fb4058bcb68986bae2bb2c04d6370f3e7218 > Signed-off-by: Murilo Opsfelder Araujo <muriloo@linux.ibm.com> > --- LGTM Reviewed-by: Greg Kurz <groug@kaod.org> > exec.c | 4 ++-- > include/qemu/mmap-alloc.h | 2 +- > util/mmap-alloc.c | 22 ++++++++++++++++------ > util/oslib-posix.c | 2 +- > 4 files changed, 20 insertions(+), 10 deletions(-) > > diff --git a/exec.c b/exec.c > index da3e635f91..0db6d8bf34 100644 > --- a/exec.c > +++ b/exec.c > @@ -1871,7 +1871,7 @@ static void *file_ram_alloc(RAMBlock *block, > if (mem_prealloc) { > os_mem_prealloc(fd, area, memory, smp_cpus, errp); > if (errp && *errp) { > - qemu_ram_munmap(area, memory); > + qemu_ram_munmap(fd, area, memory); > return NULL; > } > } > @@ -2392,7 +2392,7 @@ static void reclaim_ramblock(RAMBlock *block) > xen_invalidate_map_cache_entry(block->host); > #ifndef _WIN32 > } else if (block->fd >= 0) { > - qemu_ram_munmap(block->host, block->max_length); > + qemu_ram_munmap(block->fd, block->host, block->max_length); > close(block->fd); > #endif > } else { > diff --git a/include/qemu/mmap-alloc.h b/include/qemu/mmap-alloc.h > index 50385e3f81..ef04f0ed5b 100644 > --- a/include/qemu/mmap-alloc.h > +++ b/include/qemu/mmap-alloc.h > @@ -9,6 +9,6 @@ size_t qemu_mempath_getpagesize(const char *mem_path); > > void *qemu_ram_mmap(int fd, size_t size, size_t align, bool shared); > > -void qemu_ram_munmap(void *ptr, size_t size); > +void qemu_ram_munmap(int fd, void *ptr, size_t size); > > #endif > diff --git a/util/mmap-alloc.c b/util/mmap-alloc.c > index f71ea038c8..8565885420 100644 > --- a/util/mmap-alloc.c > +++ b/util/mmap-alloc.c > @@ -80,6 +80,7 @@ void *qemu_ram_mmap(int fd, size_t size, size_t align, bool shared) > int flags; > int guardfd; > size_t offset; > + size_t pagesize; > size_t total; > void *guardptr; > void *ptr; > @@ -100,7 +101,8 @@ void *qemu_ram_mmap(int fd, size_t size, size_t align, bool shared) > * anonymous memory is OK. > */ > flags = MAP_PRIVATE; > - if (fd == -1 || qemu_fd_getpagesize(fd) == getpagesize()) { > + pagesize = qemu_fd_getpagesize(fd); > + if (fd == -1 || pagesize == getpagesize()) { > guardfd = -1; > flags |= MAP_ANONYMOUS; > } else { > @@ -109,6 +111,7 @@ void *qemu_ram_mmap(int fd, size_t size, size_t align, bool shared) > } > #else > guardfd = -1; > + pagesize = getpagesize(); > flags = MAP_PRIVATE | MAP_ANONYMOUS; > #endif > > @@ -120,7 +123,7 @@ void *qemu_ram_mmap(int fd, size_t size, size_t align, bool shared) > > assert(is_power_of_2(align)); > /* Always align to host page size */ > - assert(align >= getpagesize()); > + assert(align >= pagesize); > > flags = MAP_FIXED; > flags |= fd == -1 ? MAP_ANONYMOUS : 0; > @@ -143,17 +146,24 @@ void *qemu_ram_mmap(int fd, size_t size, size_t align, bool shared) > * a guard page guarding against potential buffer overflows. > */ > total -= offset; > - if (total > size + getpagesize()) { > - munmap(ptr + size + getpagesize(), total - size - getpagesize()); > + if (total > size + pagesize) { > + munmap(ptr + size + pagesize, total - size - pagesize); > } > > return ptr; > } > > -void qemu_ram_munmap(void *ptr, size_t size) > +void qemu_ram_munmap(int fd, void *ptr, size_t size) > { > + size_t pagesize; > + > if (ptr) { > /* Unmap both the RAM block and the guard page */ > - munmap(ptr, size + getpagesize()); > +#if defined(__powerpc64__) && defined(__linux__) > + pagesize = qemu_fd_getpagesize(fd); > +#else > + pagesize = getpagesize(); > +#endif > + munmap(ptr, size + pagesize); > } > } > diff --git a/util/oslib-posix.c b/util/oslib-posix.c > index 4ce1ba9ca4..37c5854b9c 100644 > --- a/util/oslib-posix.c > +++ b/util/oslib-posix.c > @@ -226,7 +226,7 @@ void qemu_vfree(void *ptr) > void qemu_anon_ram_free(void *ptr, size_t size) > { > trace_qemu_anon_ram_free(ptr, size); > - qemu_ram_munmap(ptr, size); > + qemu_ram_munmap(-1, ptr, size); > } > > void qemu_set_block(int fd)
On Wed, Jan 30, 2019 at 09:36:05PM -0200, Murilo Opsfelder Araujo wrote: > The commit 7197fb4058bcb68986bae2bb2c04d6370f3e7218 ("util/mmap-alloc: > fix hugetlb support on ppc64") fixed Huge TLB mappings on ppc64. > > However, we still need to consider the underlying huge page size > during munmap() because it requires that both address and length be a > multiple of the underlying huge page size for Huge TLB mappings. > Quote from "Huge page (Huge TLB) mappings" paragraph under NOTES > section of the munmap(2) manual: > > "For munmap(), addr and length must both be a multiple of the > underlying huge page size." > > On ppc64, the munmap() in qemu_ram_munmap() does not work for Huge TLB > mappings because the mapped segment can be aligned with the underlying > huge page size, not aligned with the native system page size, as > returned by getpagesize(). > > This has the side effect of not releasing huge pages back to the pool > after a hugetlbfs file-backed memory device is hot-unplugged. > > This patch fixes the situation in qemu_ram_mmap() and > qemu_ram_munmap() by considering the underlying page size on ppc64. > > After this patch, memory hot-unplug releases huge pages back to the > pool. > > Fixes: 7197fb4058bcb68986bae2bb2c04d6370f3e7218 > Signed-off-by: Murilo Opsfelder Araujo <muriloo@linux.ibm.com> Reported-by: Balamuruhan S <bala24@linux.vnet.ibm.com> Tested-by: Balamuruhan S <bala24@linux.vnet.ibm.com> I tried to test the patch in POWER8, Distro: Fedora Host Kernel: 5.0.0-rc3-gdbaaa7d30 (upstream) Guest Kernel: 5.0.0-rc3-gdbaaa7d30 (upstream) Qemu: 3.1.50 (v3.1.0-1313-gbd08d7ec4d-dirty) (upstream) + mmap-alloc: unfold qemu_ram_mmap() + mmap-alloc: fix hugetlbfs misaligned length in ppc64 1. object_add and object_del works, Allocated 256M from host with 16M Hugepage # echo 16 > /proc/sys/vm/nr_hugepages # cat /proc/meminfo | grep Huge AnonHugePages: 737280 kB ShmemHugePages: 0 kB HugePages_Total: 16 HugePages_Free: 16 HugePages_Rsvd: 0 HugePages_Surp: 0 Hugepagesize: 16384 kB Hugetlb: 262144 kB (qemu) object_add memory-backend-file,id=mem1,size=256M,mem-path=/dev/hugepages # cat /proc/meminfo | grep Huge AnonHugePages: 737280 kB ShmemHugePages: 0 kB HugePages_Total: 16 HugePages_Free: 16 HugePages_Rsvd: 16 HugePages_Surp: 0 Hugepagesize: 16384 kB Hugetlb: 262144 kB (qemu) object_del mem1 # cat /proc/meminfo | grep Huge AnonHugePages: 671744 kB ShmemHugePages: 0 kB HugePages_Total: 16 HugePages_Free: 16 HugePages_Rsvd: 0 HugePages_Surp: 0 Hugepagesize: 16384 kB Hugetlb: 262144 kB 2. Perform complete hotplug-hotunplug works, Hotplug memory: (qemu) object_add memory-backend-file,id=mem1,size=256M,mem-path=/dev/hugepages On Host: # cat /proc/meminfo | grep Huge AnonHugePages: 737280 kB ShmemHugePages: 0 kB HugePages_Total: 16 HugePages_Free: 16 HugePages_Rsvd: 16 HugePages_Surp: 0 Hugepagesize: 16384 kB Hugetlb: 262144 kB (qemu) device_add pc-dimm,id=dimm1,memdev=mem1 # cat /proc/meminfo | grep Huge AnonHugePages: 737280 kB ShmemHugePages: 0 kB HugePages_Total: 16 HugePages_Free: 0 HugePages_Rsvd: 0 HugePages_Surp: 0 Hugepagesize: 16384 kB Hugetlb: 262144 kB Inside guest: [ 27.380848] pseries-hotplug-mem: Attempting to hot-add 1 LMB(s) at index 80000010 [ 27.420225] lpar: Attempting to resize HPT to shift 23 [ 27.619202] lpar: Hash collision while resizing HPT [ 27.620113] Unable to resize hash page table to target order 23: -28 [ 27.748767] pseries-hotplug-mem: Memory at 100000000 (drc index 80000010) was hot-added Hotunplug memory: (qemu) device_del dimm1 # cat /proc/meminfo | grep Huge AnonHugePages: 737280 kB ShmemHugePages: 0 kB HugePages_Total: 16 HugePages_Free: 0 HugePages_Rsvd: 0 HugePages_Surp: 0 Hugepagesize: 16384 kB Hugetlb: 262144 kB (qemu) object_del mem1 # cat /proc/meminfo | grep Huge AnonHugePages: 737280 kB ShmemHugePages: 0 kB HugePages_Total: 16 HugePages_Free: 16 HugePages_Rsvd: 0 HugePages_Surp: 0 Hugepagesize: 16384 kB Hugetlb: 262144 kB Inside guest: [ 29.640670] pseries-hotplug-mem: Attempting to hot-remove 1 LMB(s) at 80000010 [ 29.710276] Offlined Pages 4096 [ 29.733824] lpar: Attempting to resize HPT to shift 22 [ 29.880381] lpar: Hash collision while resizing HPT [ 29.881521] Unable to resize hash page table to target order 22: -28 [ 29.900542] pseries-hotplug-mem: Memory at 100000000 (drc index 80000010) was hot-removed Thanks Murilo, -- Bala > --- > exec.c | 4 ++-- > include/qemu/mmap-alloc.h | 2 +- > util/mmap-alloc.c | 22 ++++++++++++++++------ > util/oslib-posix.c | 2 +- > 4 files changed, 20 insertions(+), 10 deletions(-) > > diff --git a/exec.c b/exec.c > index da3e635f91..0db6d8bf34 100644 > --- a/exec.c > +++ b/exec.c > @@ -1871,7 +1871,7 @@ static void *file_ram_alloc(RAMBlock *block, > if (mem_prealloc) { > os_mem_prealloc(fd, area, memory, smp_cpus, errp); > if (errp && *errp) { > - qemu_ram_munmap(area, memory); > + qemu_ram_munmap(fd, area, memory); > return NULL; > } > } > @@ -2392,7 +2392,7 @@ static void reclaim_ramblock(RAMBlock *block) > xen_invalidate_map_cache_entry(block->host); > #ifndef _WIN32 > } else if (block->fd >= 0) { > - qemu_ram_munmap(block->host, block->max_length); > + qemu_ram_munmap(block->fd, block->host, block->max_length); > close(block->fd); > #endif > } else { > diff --git a/include/qemu/mmap-alloc.h b/include/qemu/mmap-alloc.h > index 50385e3f81..ef04f0ed5b 100644 > --- a/include/qemu/mmap-alloc.h > +++ b/include/qemu/mmap-alloc.h > @@ -9,6 +9,6 @@ size_t qemu_mempath_getpagesize(const char *mem_path); > > void *qemu_ram_mmap(int fd, size_t size, size_t align, bool shared); > > -void qemu_ram_munmap(void *ptr, size_t size); > +void qemu_ram_munmap(int fd, void *ptr, size_t size); > > #endif > diff --git a/util/mmap-alloc.c b/util/mmap-alloc.c > index f71ea038c8..8565885420 100644 > --- a/util/mmap-alloc.c > +++ b/util/mmap-alloc.c > @@ -80,6 +80,7 @@ void *qemu_ram_mmap(int fd, size_t size, size_t align, bool shared) > int flags; > int guardfd; > size_t offset; > + size_t pagesize; > size_t total; > void *guardptr; > void *ptr; > @@ -100,7 +101,8 @@ void *qemu_ram_mmap(int fd, size_t size, size_t align, bool shared) > * anonymous memory is OK. > */ > flags = MAP_PRIVATE; > - if (fd == -1 || qemu_fd_getpagesize(fd) == getpagesize()) { > + pagesize = qemu_fd_getpagesize(fd); > + if (fd == -1 || pagesize == getpagesize()) { > guardfd = -1; > flags |= MAP_ANONYMOUS; > } else { > @@ -109,6 +111,7 @@ void *qemu_ram_mmap(int fd, size_t size, size_t align, bool shared) > } > #else > guardfd = -1; > + pagesize = getpagesize(); > flags = MAP_PRIVATE | MAP_ANONYMOUS; > #endif > > @@ -120,7 +123,7 @@ void *qemu_ram_mmap(int fd, size_t size, size_t align, bool shared) > > assert(is_power_of_2(align)); > /* Always align to host page size */ > - assert(align >= getpagesize()); > + assert(align >= pagesize); > > flags = MAP_FIXED; > flags |= fd == -1 ? MAP_ANONYMOUS : 0; > @@ -143,17 +146,24 @@ void *qemu_ram_mmap(int fd, size_t size, size_t align, bool shared) > * a guard page guarding against potential buffer overflows. > */ > total -= offset; > - if (total > size + getpagesize()) { > - munmap(ptr + size + getpagesize(), total - size - getpagesize()); > + if (total > size + pagesize) { > + munmap(ptr + size + pagesize, total - size - pagesize); > } > > return ptr; > } > > -void qemu_ram_munmap(void *ptr, size_t size) > +void qemu_ram_munmap(int fd, void *ptr, size_t size) > { > + size_t pagesize; > + > if (ptr) { > /* Unmap both the RAM block and the guard page */ > - munmap(ptr, size + getpagesize()); > +#if defined(__powerpc64__) && defined(__linux__) > + pagesize = qemu_fd_getpagesize(fd); > +#else > + pagesize = getpagesize(); > +#endif > + munmap(ptr, size + pagesize); > } > } > diff --git a/util/oslib-posix.c b/util/oslib-posix.c > index 4ce1ba9ca4..37c5854b9c 100644 > --- a/util/oslib-posix.c > +++ b/util/oslib-posix.c > @@ -226,7 +226,7 @@ void qemu_vfree(void *ptr) > void qemu_anon_ram_free(void *ptr, size_t size) > { > trace_qemu_anon_ram_free(ptr, size); > - qemu_ram_munmap(ptr, size); > + qemu_ram_munmap(-1, ptr, size); > } > > void qemu_set_block(int fd) > -- > 2.20.1 > >
diff --git a/exec.c b/exec.c index da3e635f91..0db6d8bf34 100644 --- a/exec.c +++ b/exec.c @@ -1871,7 +1871,7 @@ static void *file_ram_alloc(RAMBlock *block, if (mem_prealloc) { os_mem_prealloc(fd, area, memory, smp_cpus, errp); if (errp && *errp) { - qemu_ram_munmap(area, memory); + qemu_ram_munmap(fd, area, memory); return NULL; } } @@ -2392,7 +2392,7 @@ static void reclaim_ramblock(RAMBlock *block) xen_invalidate_map_cache_entry(block->host); #ifndef _WIN32 } else if (block->fd >= 0) { - qemu_ram_munmap(block->host, block->max_length); + qemu_ram_munmap(block->fd, block->host, block->max_length); close(block->fd); #endif } else { diff --git a/include/qemu/mmap-alloc.h b/include/qemu/mmap-alloc.h index 50385e3f81..ef04f0ed5b 100644 --- a/include/qemu/mmap-alloc.h +++ b/include/qemu/mmap-alloc.h @@ -9,6 +9,6 @@ size_t qemu_mempath_getpagesize(const char *mem_path); void *qemu_ram_mmap(int fd, size_t size, size_t align, bool shared); -void qemu_ram_munmap(void *ptr, size_t size); +void qemu_ram_munmap(int fd, void *ptr, size_t size); #endif diff --git a/util/mmap-alloc.c b/util/mmap-alloc.c index f71ea038c8..8565885420 100644 --- a/util/mmap-alloc.c +++ b/util/mmap-alloc.c @@ -80,6 +80,7 @@ void *qemu_ram_mmap(int fd, size_t size, size_t align, bool shared) int flags; int guardfd; size_t offset; + size_t pagesize; size_t total; void *guardptr; void *ptr; @@ -100,7 +101,8 @@ void *qemu_ram_mmap(int fd, size_t size, size_t align, bool shared) * anonymous memory is OK. */ flags = MAP_PRIVATE; - if (fd == -1 || qemu_fd_getpagesize(fd) == getpagesize()) { + pagesize = qemu_fd_getpagesize(fd); + if (fd == -1 || pagesize == getpagesize()) { guardfd = -1; flags |= MAP_ANONYMOUS; } else { @@ -109,6 +111,7 @@ void *qemu_ram_mmap(int fd, size_t size, size_t align, bool shared) } #else guardfd = -1; + pagesize = getpagesize(); flags = MAP_PRIVATE | MAP_ANONYMOUS; #endif @@ -120,7 +123,7 @@ void *qemu_ram_mmap(int fd, size_t size, size_t align, bool shared) assert(is_power_of_2(align)); /* Always align to host page size */ - assert(align >= getpagesize()); + assert(align >= pagesize); flags = MAP_FIXED; flags |= fd == -1 ? MAP_ANONYMOUS : 0; @@ -143,17 +146,24 @@ void *qemu_ram_mmap(int fd, size_t size, size_t align, bool shared) * a guard page guarding against potential buffer overflows. */ total -= offset; - if (total > size + getpagesize()) { - munmap(ptr + size + getpagesize(), total - size - getpagesize()); + if (total > size + pagesize) { + munmap(ptr + size + pagesize, total - size - pagesize); } return ptr; } -void qemu_ram_munmap(void *ptr, size_t size) +void qemu_ram_munmap(int fd, void *ptr, size_t size) { + size_t pagesize; + if (ptr) { /* Unmap both the RAM block and the guard page */ - munmap(ptr, size + getpagesize()); +#if defined(__powerpc64__) && defined(__linux__) + pagesize = qemu_fd_getpagesize(fd); +#else + pagesize = getpagesize(); +#endif + munmap(ptr, size + pagesize); } } diff --git a/util/oslib-posix.c b/util/oslib-posix.c index 4ce1ba9ca4..37c5854b9c 100644 --- a/util/oslib-posix.c +++ b/util/oslib-posix.c @@ -226,7 +226,7 @@ void qemu_vfree(void *ptr) void qemu_anon_ram_free(void *ptr, size_t size) { trace_qemu_anon_ram_free(ptr, size); - qemu_ram_munmap(ptr, size); + qemu_ram_munmap(-1, ptr, size); } void qemu_set_block(int fd)
The commit 7197fb4058bcb68986bae2bb2c04d6370f3e7218 ("util/mmap-alloc: fix hugetlb support on ppc64") fixed Huge TLB mappings on ppc64. However, we still need to consider the underlying huge page size during munmap() because it requires that both address and length be a multiple of the underlying huge page size for Huge TLB mappings. Quote from "Huge page (Huge TLB) mappings" paragraph under NOTES section of the munmap(2) manual: "For munmap(), addr and length must both be a multiple of the underlying huge page size." On ppc64, the munmap() in qemu_ram_munmap() does not work for Huge TLB mappings because the mapped segment can be aligned with the underlying huge page size, not aligned with the native system page size, as returned by getpagesize(). This has the side effect of not releasing huge pages back to the pool after a hugetlbfs file-backed memory device is hot-unplugged. This patch fixes the situation in qemu_ram_mmap() and qemu_ram_munmap() by considering the underlying page size on ppc64. After this patch, memory hot-unplug releases huge pages back to the pool. Fixes: 7197fb4058bcb68986bae2bb2c04d6370f3e7218 Signed-off-by: Murilo Opsfelder Araujo <muriloo@linux.ibm.com> --- exec.c | 4 ++-- include/qemu/mmap-alloc.h | 2 +- util/mmap-alloc.c | 22 ++++++++++++++++------ util/oslib-posix.c | 2 +- 4 files changed, 20 insertions(+), 10 deletions(-)