| Message ID | 20221222190022.134380-1-urezki@gmail.com (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | [v3,1/3] mm: vmalloc: Avoid calling __find_vmap_area() twice in __vunmap() | expand |
n Thu, Dec 22, 2022 at 08:00:20PM +0100, Uladzislau Rezki (Sony) wrote: > Currently the __vunmap() path calls __find_vmap_area() twice. Once on > entry to check that the area exists, then inside the remove_vm_area() > function which also performs a new search for the VA. > > In order to improvie it from a performance point of view we split > remove_vm_area() into two new parts: > - find_unlink_vmap_area() that does a search and unlink from tree; > - __remove_vm_area() that removes without searching. > > In this case there is no any functional change for remove_vm_area() > whereas vm_remove_mappings(), where a second search happens, switches > to the __remove_vm_area() variant where the already detached VA is > passed as a parameter, so there is no need to find it again. > > Performance wise, i use test_vmalloc.sh with 32 threads doing alloc > free on a 64-CPUs-x86_64-box: > > perf without this patch: > - 31.41% 0.50% vmalloc_test/10 [kernel.vmlinux] [k] __vunmap > - 30.92% __vunmap > - 17.67% _raw_spin_lock > native_queued_spin_lock_slowpath > - 12.33% remove_vm_area > - 11.79% free_vmap_area_noflush > - 11.18% _raw_spin_lock > native_queued_spin_lock_slowpath > 0.76% free_unref_page > > perf with this patch: > - 11.35% 0.13% vmalloc_test/14 [kernel.vmlinux] [k] __vunmap > - 11.23% __vunmap > - 8.28% find_unlink_vmap_area > - 7.95% _raw_spin_lock > 7.44% native_queued_spin_lock_slowpath > - 1.93% free_vmap_area_noflush > - 0.56% _raw_spin_lock > 0.53% native_queued_spin_lock_slowpath > 0.60% __vunmap_range_noflush > > __vunmap() consumes around ~20% less CPU cycles on this test. > > v2 -> v3: > - update commit message; > - rename the vm_remove_mappings() to the va_remove_mappings(); > - move va-unlinking to the callers so the free_vmap_area_noflush() > now expects a VA that has been disconnected; > - eliminate a local variable in the remove_vm_area(). > > Reported-by: Roman Gushchin <roman.gushchin@linux.dev> > Signed-off-by: Uladzislau Rezki (Sony) <urezki@gmail.com> > --- > mm/vmalloc.c | 77 ++++++++++++++++++++++++++++++++-------------------- > 1 file changed, 47 insertions(+), 30 deletions(-) > > diff --git a/mm/vmalloc.c b/mm/vmalloc.c > index 9e30f0b39203..eb91ecaa7277 100644 > --- a/mm/vmalloc.c > +++ b/mm/vmalloc.c > @@ -1815,9 +1815,9 @@ static void drain_vmap_area_work(struct work_struct *work) > } > > /* > - * Free a vmap area, caller ensuring that the area has been unmapped > - * and flush_cache_vunmap had been called for the correct range > - * previously. > + * Free a vmap area, caller ensuring that the area has been unmapped, > + * unlinked and flush_cache_vunmap had been called for the correct > + * range previously. > */ > static void free_vmap_area_noflush(struct vmap_area *va) > { > @@ -1825,9 +1825,8 @@ static void free_vmap_area_noflush(struct vmap_area *va) > unsigned long va_start = va->va_start; > unsigned long nr_lazy; > > - spin_lock(&vmap_area_lock); > - unlink_va(va, &vmap_area_root); > - spin_unlock(&vmap_area_lock); > + if (WARN_ON_ONCE(!list_empty(&va->list))) > + return; > > nr_lazy = atomic_long_add_return((va->va_end - va->va_start) >> > PAGE_SHIFT, &vmap_lazy_nr); > @@ -1871,6 +1870,19 @@ struct vmap_area *find_vmap_area(unsigned long addr) > return va; > } > > +static struct vmap_area *find_unlink_vmap_area(unsigned long addr) > +{ > + struct vmap_area *va; > + > + spin_lock(&vmap_area_lock); > + va = __find_vmap_area(addr, &vmap_area_root); > + if (va) > + unlink_va(va, &vmap_area_root); > + spin_unlock(&vmap_area_lock); > + > + return va; > +} > + > /*** Per cpu kva allocator ***/ > > /* > @@ -2015,6 +2027,10 @@ static void free_vmap_block(struct vmap_block *vb) > tmp = xa_erase(&vmap_blocks, addr_to_vb_idx(vb->va->va_start)); > BUG_ON(tmp != vb); > > + spin_lock(&vmap_area_lock); > + unlink_va(vb->va, &vmap_area_root); > + spin_unlock(&vmap_area_lock); > + > free_vmap_area_noflush(vb->va); > kfree_rcu(vb, rcu_head); > } > @@ -2591,6 +2607,20 @@ struct vm_struct *find_vm_area(const void *addr) > return va->vm; > } > > +static struct vm_struct *__remove_vm_area(struct vmap_area *va) > +{ > + struct vm_struct *vm; > + > + if (!va || !va->vm) > + return NULL; > + > + vm = va->vm; > + kasan_free_module_shadow(vm); > + free_unmap_vmap_area(va); > + > + return vm; > +} > + > /** > * remove_vm_area - find and remove a continuous kernel virtual area > * @addr: base address > @@ -2603,26 +2633,10 @@ struct vm_struct *find_vm_area(const void *addr) > */ > struct vm_struct *remove_vm_area(const void *addr) > { > - struct vmap_area *va; > - > might_sleep(); > > - spin_lock(&vmap_area_lock); > - va = __find_vmap_area((unsigned long)addr, &vmap_area_root); > - if (va && va->vm) { > - struct vm_struct *vm = va->vm; > - > - va->vm = NULL; > - spin_unlock(&vmap_area_lock); > - > - kasan_free_module_shadow(vm); > - free_unmap_vmap_area(va); > - > - return vm; > - } > - > - spin_unlock(&vmap_area_lock); > - return NULL; > + return __remove_vm_area( > + find_unlink_vmap_area((unsigned long) addr)); > } > > static inline void set_area_direct_map(const struct vm_struct *area, > @@ -2636,16 +2650,17 @@ static inline void set_area_direct_map(const struct vm_struct *area, > set_direct_map(area->pages[i]); > } > > -/* Handle removing and resetting vm mappings related to the vm_struct. */ > -static void vm_remove_mappings(struct vm_struct *area, int deallocate_pages) > +/* Handle removing and resetting vm mappings related to the VA's vm_struct. */ > +static void va_remove_mappings(struct vmap_area *va, int deallocate_pages) > { > + struct vm_struct *area = va->vm; > unsigned long start = ULONG_MAX, end = 0; > unsigned int page_order = vm_area_page_order(area); > int flush_reset = area->flags & VM_FLUSH_RESET_PERMS; > int flush_dmap = 0; > int i; > > - remove_vm_area(area->addr); > + __remove_vm_area(va); > > /* If this is not VM_FLUSH_RESET_PERMS memory, no need for the below. */ > if (!flush_reset) > @@ -2690,6 +2705,7 @@ static void vm_remove_mappings(struct vm_struct *area, int deallocate_pages) > static void __vunmap(const void *addr, int deallocate_pages) > { > struct vm_struct *area; > + struct vmap_area *va; > > if (!addr) > return; > @@ -2698,19 +2714,20 @@ static void __vunmap(const void *addr, int deallocate_pages) > addr)) > return; > > - area = find_vm_area(addr); > - if (unlikely(!area)) { > + va = find_unlink_vmap_area((unsigned long)addr); > + if (unlikely(!va)) { > WARN(1, KERN_ERR "Trying to vfree() nonexistent vm area (%p)\n", > addr); > return; > } > > + area = va->vm; > debug_check_no_locks_freed(area->addr, get_vm_area_size(area)); > debug_check_no_obj_freed(area->addr, get_vm_area_size(area)); > > kasan_poison_vmalloc(area->addr, get_vm_area_size(area)); > > - vm_remove_mappings(area, deallocate_pages); > + va_remove_mappings(va, deallocate_pages); > > if (deallocate_pages) { > int i; > -- > 2.30.2 > All looks good to me! Great work! Feel free to add the below to all patches in series:- Reviewed-by: Lorenzo Stoakes <lstoakes@gmail.com>
On Thu, Dec 22, 2022 at 08:00:20PM +0100, Uladzislau Rezki (Sony) wrote: > @@ -1825,9 +1825,8 @@ static void free_vmap_area_noflush(struct vmap_area *va) > unsigned long va_start = va->va_start; > unsigned long nr_lazy; > > - spin_lock(&vmap_area_lock); > - unlink_va(va, &vmap_area_root); > - spin_unlock(&vmap_area_lock); > + if (WARN_ON_ONCE(!list_empty(&va->list))) > + return; I'd just drop this check as the function is not exported. Otherwise looks good: Reviewed-by: Christoph Hellwig <hch@lst.de>
On Thu, Dec 22, 2022 at 08:06:11PM +0000, Lorenzo Stoakes wrote: > n Thu, Dec 22, 2022 at 08:00:20PM +0100, Uladzislau Rezki (Sony) wrote: > > Currently the __vunmap() path calls __find_vmap_area() twice. Once on > > entry to check that the area exists, then inside the remove_vm_area() > > function which also performs a new search for the VA. > > > > In order to improvie it from a performance point of view we split > > remove_vm_area() into two new parts: > > - find_unlink_vmap_area() that does a search and unlink from tree; > > - __remove_vm_area() that removes without searching. > > > > In this case there is no any functional change for remove_vm_area() > > whereas vm_remove_mappings(), where a second search happens, switches > > to the __remove_vm_area() variant where the already detached VA is > > passed as a parameter, so there is no need to find it again. > > > > Performance wise, i use test_vmalloc.sh with 32 threads doing alloc > > free on a 64-CPUs-x86_64-box: > > > > perf without this patch: > > - 31.41% 0.50% vmalloc_test/10 [kernel.vmlinux] [k] __vunmap > > - 30.92% __vunmap > > - 17.67% _raw_spin_lock > > native_queued_spin_lock_slowpath > > - 12.33% remove_vm_area > > - 11.79% free_vmap_area_noflush > > - 11.18% _raw_spin_lock > > native_queued_spin_lock_slowpath > > 0.76% free_unref_page > > > > perf with this patch: > > - 11.35% 0.13% vmalloc_test/14 [kernel.vmlinux] [k] __vunmap > > - 11.23% __vunmap > > - 8.28% find_unlink_vmap_area > > - 7.95% _raw_spin_lock > > 7.44% native_queued_spin_lock_slowpath > > - 1.93% free_vmap_area_noflush > > - 0.56% _raw_spin_lock > > 0.53% native_queued_spin_lock_slowpath > > 0.60% __vunmap_range_noflush > > > > __vunmap() consumes around ~20% less CPU cycles on this test. > > > > v2 -> v3: > > - update commit message; > > - rename the vm_remove_mappings() to the va_remove_mappings(); > > - move va-unlinking to the callers so the free_vmap_area_noflush() > > now expects a VA that has been disconnected; > > - eliminate a local variable in the remove_vm_area(). > > > > Reported-by: Roman Gushchin <roman.gushchin@linux.dev> > > Signed-off-by: Uladzislau Rezki (Sony) <urezki@gmail.com> > > --- > > mm/vmalloc.c | 77 ++++++++++++++++++++++++++++++++-------------------- > > 1 file changed, 47 insertions(+), 30 deletions(-) > > > > diff --git a/mm/vmalloc.c b/mm/vmalloc.c > > index 9e30f0b39203..eb91ecaa7277 100644 > > --- a/mm/vmalloc.c > > +++ b/mm/vmalloc.c > > @@ -1815,9 +1815,9 @@ static void drain_vmap_area_work(struct work_struct *work) > > } > > > > /* > > - * Free a vmap area, caller ensuring that the area has been unmapped > > - * and flush_cache_vunmap had been called for the correct range > > - * previously. > > + * Free a vmap area, caller ensuring that the area has been unmapped, > > + * unlinked and flush_cache_vunmap had been called for the correct > > + * range previously. > > */ > > static void free_vmap_area_noflush(struct vmap_area *va) > > { > > @@ -1825,9 +1825,8 @@ static void free_vmap_area_noflush(struct vmap_area *va) > > unsigned long va_start = va->va_start; > > unsigned long nr_lazy; > > > > - spin_lock(&vmap_area_lock); > > - unlink_va(va, &vmap_area_root); > > - spin_unlock(&vmap_area_lock); > > + if (WARN_ON_ONCE(!list_empty(&va->list))) > > + return; > > > > nr_lazy = atomic_long_add_return((va->va_end - va->va_start) >> > > PAGE_SHIFT, &vmap_lazy_nr); > > @@ -1871,6 +1870,19 @@ struct vmap_area *find_vmap_area(unsigned long addr) > > return va; > > } > > > > +static struct vmap_area *find_unlink_vmap_area(unsigned long addr) > > +{ > > + struct vmap_area *va; > > + > > + spin_lock(&vmap_area_lock); > > + va = __find_vmap_area(addr, &vmap_area_root); > > + if (va) > > + unlink_va(va, &vmap_area_root); > > + spin_unlock(&vmap_area_lock); > > + > > + return va; > > +} > > + > > /*** Per cpu kva allocator ***/ > > > > /* > > @@ -2015,6 +2027,10 @@ static void free_vmap_block(struct vmap_block *vb) > > tmp = xa_erase(&vmap_blocks, addr_to_vb_idx(vb->va->va_start)); > > BUG_ON(tmp != vb); > > > > + spin_lock(&vmap_area_lock); > > + unlink_va(vb->va, &vmap_area_root); > > + spin_unlock(&vmap_area_lock); > > + > > free_vmap_area_noflush(vb->va); > > kfree_rcu(vb, rcu_head); > > } > > @@ -2591,6 +2607,20 @@ struct vm_struct *find_vm_area(const void *addr) > > return va->vm; > > } > > > > +static struct vm_struct *__remove_vm_area(struct vmap_area *va) > > +{ > > + struct vm_struct *vm; > > + > > + if (!va || !va->vm) > > + return NULL; > > + > > + vm = va->vm; > > + kasan_free_module_shadow(vm); > > + free_unmap_vmap_area(va); > > + > > + return vm; > > +} > > + > > /** > > * remove_vm_area - find and remove a continuous kernel virtual area > > * @addr: base address > > @@ -2603,26 +2633,10 @@ struct vm_struct *find_vm_area(const void *addr) > > */ > > struct vm_struct *remove_vm_area(const void *addr) > > { > > - struct vmap_area *va; > > - > > might_sleep(); > > > > - spin_lock(&vmap_area_lock); > > - va = __find_vmap_area((unsigned long)addr, &vmap_area_root); > > - if (va && va->vm) { > > - struct vm_struct *vm = va->vm; > > - > > - va->vm = NULL; > > - spin_unlock(&vmap_area_lock); > > - > > - kasan_free_module_shadow(vm); > > - free_unmap_vmap_area(va); > > - > > - return vm; > > - } > > - > > - spin_unlock(&vmap_area_lock); > > - return NULL; > > + return __remove_vm_area( > > + find_unlink_vmap_area((unsigned long) addr)); > > } > > > > static inline void set_area_direct_map(const struct vm_struct *area, > > @@ -2636,16 +2650,17 @@ static inline void set_area_direct_map(const struct vm_struct *area, > > set_direct_map(area->pages[i]); > > } > > > > -/* Handle removing and resetting vm mappings related to the vm_struct. */ > > -static void vm_remove_mappings(struct vm_struct *area, int deallocate_pages) > > +/* Handle removing and resetting vm mappings related to the VA's vm_struct. */ > > +static void va_remove_mappings(struct vmap_area *va, int deallocate_pages) > > { > > + struct vm_struct *area = va->vm; > > unsigned long start = ULONG_MAX, end = 0; > > unsigned int page_order = vm_area_page_order(area); > > int flush_reset = area->flags & VM_FLUSH_RESET_PERMS; > > int flush_dmap = 0; > > int i; > > > > - remove_vm_area(area->addr); > > + __remove_vm_area(va); > > > > /* If this is not VM_FLUSH_RESET_PERMS memory, no need for the below. */ > > if (!flush_reset) > > @@ -2690,6 +2705,7 @@ static void vm_remove_mappings(struct vm_struct *area, int deallocate_pages) > > static void __vunmap(const void *addr, int deallocate_pages) > > { > > struct vm_struct *area; > > + struct vmap_area *va; > > > > if (!addr) > > return; > > @@ -2698,19 +2714,20 @@ static void __vunmap(const void *addr, int deallocate_pages) > > addr)) > > return; > > > > - area = find_vm_area(addr); > > - if (unlikely(!area)) { > > + va = find_unlink_vmap_area((unsigned long)addr); > > + if (unlikely(!va)) { > > WARN(1, KERN_ERR "Trying to vfree() nonexistent vm area (%p)\n", > > addr); > > return; > > } > > > > + area = va->vm; > > debug_check_no_locks_freed(area->addr, get_vm_area_size(area)); > > debug_check_no_obj_freed(area->addr, get_vm_area_size(area)); > > > > kasan_poison_vmalloc(area->addr, get_vm_area_size(area)); > > > > - vm_remove_mappings(area, deallocate_pages); > > + va_remove_mappings(va, deallocate_pages); > > > > if (deallocate_pages) { > > int i; > > -- > > 2.30.2 > > > > All looks good to me! Great work! Feel free to add the below to all patches in series:- > > Reviewed-by: Lorenzo Stoakes <lstoakes@gmail.com> > Added :) Thank you for review! -- Uladzislau Rezki
On Fri, Dec 23, 2022 at 12:19:26AM -0800, Christoph Hellwig wrote: > On Thu, Dec 22, 2022 at 08:00:20PM +0100, Uladzislau Rezki (Sony) wrote: > > @@ -1825,9 +1825,8 @@ static void free_vmap_area_noflush(struct vmap_area *va) > > unsigned long va_start = va->va_start; > > unsigned long nr_lazy; > > > > - spin_lock(&vmap_area_lock); > > - unlink_va(va, &vmap_area_root); > > - spin_unlock(&vmap_area_lock); > > + if (WARN_ON_ONCE(!list_empty(&va->list))) > > + return; > > I'd just drop this check as the function is not exported. > > > Otherwise looks good: > > Reviewed-by: Christoph Hellwig <hch@lst.de> > Thanks! -- Uladzislau Rezki
diff --git a/mm/vmalloc.c b/mm/vmalloc.c index 9e30f0b39203..eb91ecaa7277 100644 --- a/mm/vmalloc.c +++ b/mm/vmalloc.c @@ -1815,9 +1815,9 @@ static void drain_vmap_area_work(struct work_struct *work) } /* - * Free a vmap area, caller ensuring that the area has been unmapped - * and flush_cache_vunmap had been called for the correct range - * previously. + * Free a vmap area, caller ensuring that the area has been unmapped, + * unlinked and flush_cache_vunmap had been called for the correct + * range previously. */ static void free_vmap_area_noflush(struct vmap_area *va) { @@ -1825,9 +1825,8 @@ static void free_vmap_area_noflush(struct vmap_area *va) unsigned long va_start = va->va_start; unsigned long nr_lazy; - spin_lock(&vmap_area_lock); - unlink_va(va, &vmap_area_root); - spin_unlock(&vmap_area_lock); + if (WARN_ON_ONCE(!list_empty(&va->list))) + return; nr_lazy = atomic_long_add_return((va->va_end - va->va_start) >> PAGE_SHIFT, &vmap_lazy_nr); @@ -1871,6 +1870,19 @@ struct vmap_area *find_vmap_area(unsigned long addr) return va; } +static struct vmap_area *find_unlink_vmap_area(unsigned long addr) +{ + struct vmap_area *va; + + spin_lock(&vmap_area_lock); + va = __find_vmap_area(addr, &vmap_area_root); + if (va) + unlink_va(va, &vmap_area_root); + spin_unlock(&vmap_area_lock); + + return va; +} + /*** Per cpu kva allocator ***/ /* @@ -2015,6 +2027,10 @@ static void free_vmap_block(struct vmap_block *vb) tmp = xa_erase(&vmap_blocks, addr_to_vb_idx(vb->va->va_start)); BUG_ON(tmp != vb); + spin_lock(&vmap_area_lock); + unlink_va(vb->va, &vmap_area_root); + spin_unlock(&vmap_area_lock); + free_vmap_area_noflush(vb->va); kfree_rcu(vb, rcu_head); } @@ -2591,6 +2607,20 @@ struct vm_struct *find_vm_area(const void *addr) return va->vm; } +static struct vm_struct *__remove_vm_area(struct vmap_area *va) +{ + struct vm_struct *vm; + + if (!va || !va->vm) + return NULL; + + vm = va->vm; + kasan_free_module_shadow(vm); + free_unmap_vmap_area(va); + + return vm; +} + /** * remove_vm_area - find and remove a continuous kernel virtual area * @addr: base address @@ -2603,26 +2633,10 @@ struct vm_struct *find_vm_area(const void *addr) */ struct vm_struct *remove_vm_area(const void *addr) { - struct vmap_area *va; - might_sleep(); - spin_lock(&vmap_area_lock); - va = __find_vmap_area((unsigned long)addr, &vmap_area_root); - if (va && va->vm) { - struct vm_struct *vm = va->vm; - - va->vm = NULL; - spin_unlock(&vmap_area_lock); - - kasan_free_module_shadow(vm); - free_unmap_vmap_area(va); - - return vm; - } - - spin_unlock(&vmap_area_lock); - return NULL; + return __remove_vm_area( + find_unlink_vmap_area((unsigned long) addr)); } static inline void set_area_direct_map(const struct vm_struct *area, @@ -2636,16 +2650,17 @@ static inline void set_area_direct_map(const struct vm_struct *area, set_direct_map(area->pages[i]); } -/* Handle removing and resetting vm mappings related to the vm_struct. */ -static void vm_remove_mappings(struct vm_struct *area, int deallocate_pages) +/* Handle removing and resetting vm mappings related to the VA's vm_struct. */ +static void va_remove_mappings(struct vmap_area *va, int deallocate_pages) { + struct vm_struct *area = va->vm; unsigned long start = ULONG_MAX, end = 0; unsigned int page_order = vm_area_page_order(area); int flush_reset = area->flags & VM_FLUSH_RESET_PERMS; int flush_dmap = 0; int i; - remove_vm_area(area->addr); + __remove_vm_area(va); /* If this is not VM_FLUSH_RESET_PERMS memory, no need for the below. */ if (!flush_reset) @@ -2690,6 +2705,7 @@ static void vm_remove_mappings(struct vm_struct *area, int deallocate_pages) static void __vunmap(const void *addr, int deallocate_pages) { struct vm_struct *area; + struct vmap_area *va; if (!addr) return; @@ -2698,19 +2714,20 @@ static void __vunmap(const void *addr, int deallocate_pages) addr)) return; - area = find_vm_area(addr); - if (unlikely(!area)) { + va = find_unlink_vmap_area((unsigned long)addr); + if (unlikely(!va)) { WARN(1, KERN_ERR "Trying to vfree() nonexistent vm area (%p)\n", addr); return; } + area = va->vm; debug_check_no_locks_freed(area->addr, get_vm_area_size(area)); debug_check_no_obj_freed(area->addr, get_vm_area_size(area)); kasan_poison_vmalloc(area->addr, get_vm_area_size(area)); - vm_remove_mappings(area, deallocate_pages); + va_remove_mappings(va, deallocate_pages); if (deallocate_pages) { int i;
Currently the __vunmap() path calls __find_vmap_area() twice. Once on entry to check that the area exists, then inside the remove_vm_area() function which also performs a new search for the VA. In order to improvie it from a performance point of view we split remove_vm_area() into two new parts: - find_unlink_vmap_area() that does a search and unlink from tree; - __remove_vm_area() that removes without searching. In this case there is no any functional change for remove_vm_area() whereas vm_remove_mappings(), where a second search happens, switches to the __remove_vm_area() variant where the already detached VA is passed as a parameter, so there is no need to find it again. Performance wise, i use test_vmalloc.sh with 32 threads doing alloc free on a 64-CPUs-x86_64-box: perf without this patch: - 31.41% 0.50% vmalloc_test/10 [kernel.vmlinux] [k] __vunmap - 30.92% __vunmap - 17.67% _raw_spin_lock native_queued_spin_lock_slowpath - 12.33% remove_vm_area - 11.79% free_vmap_area_noflush - 11.18% _raw_spin_lock native_queued_spin_lock_slowpath 0.76% free_unref_page perf with this patch: - 11.35% 0.13% vmalloc_test/14 [kernel.vmlinux] [k] __vunmap - 11.23% __vunmap - 8.28% find_unlink_vmap_area - 7.95% _raw_spin_lock 7.44% native_queued_spin_lock_slowpath - 1.93% free_vmap_area_noflush - 0.56% _raw_spin_lock 0.53% native_queued_spin_lock_slowpath 0.60% __vunmap_range_noflush __vunmap() consumes around ~20% less CPU cycles on this test. v2 -> v3: - update commit message; - rename the vm_remove_mappings() to the va_remove_mappings(); - move va-unlinking to the callers so the free_vmap_area_noflush() now expects a VA that has been disconnected; - eliminate a local variable in the remove_vm_area(). Reported-by: Roman Gushchin <roman.gushchin@linux.dev> Signed-off-by: Uladzislau Rezki (Sony) <urezki@gmail.com> --- mm/vmalloc.c | 77 ++++++++++++++++++++++++++++++++-------------------- 1 file changed, 47 insertions(+), 30 deletions(-)