| Message ID | 20220603145719.1012094-3-matenajakub@gmail.com (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | Refactor of vma_merge and new merge call | expand |
On 6/3/22 16:57, Jakub Matěna wrote: > When mremap call results in expansion, it might be possible to merge the > VMA with the next VMA which might become adjacent. This patch adds > vma_merge call after the expansion is done to try and merge. > > Signed-off-by: Jakub Matěna <matenajakub@gmail.com> Reviewed-by: Vlastimil Babka <vbabka@suse.cz> > --- > mm/mremap.c | 19 +++++++++- > tools/testing/selftests/vm/mremap_test.c | 47 +++++++++++++++++++++++- > 2 files changed, 63 insertions(+), 3 deletions(-) > > diff --git a/mm/mremap.c b/mm/mremap.c > index 0b93fac76851..66970dcd636a 100644 > --- a/mm/mremap.c > +++ b/mm/mremap.c > @@ -9,6 +9,7 @@ > */ > > #include <linux/mm.h> > +#include <linux/mm_inline.h> > #include <linux/hugetlb.h> > #include <linux/shm.h> > #include <linux/ksm.h> > @@ -23,6 +24,7 @@ > #include <linux/mmu_notifier.h> > #include <linux/uaccess.h> > #include <linux/userfaultfd_k.h> > +#include <linux/mempolicy.h> > > #include <asm/cacheflush.h> > #include <asm/tlb.h> > @@ -1014,6 +1016,9 @@ SYSCALL_DEFINE5(mremap, unsigned long, addr, unsigned long, old_len, > /* can we just expand the current mapping? */ > if (vma_expandable(vma, new_len - old_len)) { > long pages = (new_len - old_len) >> PAGE_SHIFT; > + unsigned long extension_start = addr + old_len; > + unsigned long extension_end = addr + new_len; > + pgoff_t extension_pgoff = vma->vm_pgoff + (old_len >> PAGE_SHIFT); > > if (vma->vm_flags & VM_ACCOUNT) { > if (security_vm_enough_memory_mm(mm, pages)) { > @@ -1022,8 +1027,18 @@ SYSCALL_DEFINE5(mremap, unsigned long, addr, unsigned long, old_len, > } > } > > - if (vma_adjust(vma, vma->vm_start, addr + new_len, > - vma->vm_pgoff, NULL)) { > + /* > + * Function vma_merge() is called on the extension we are adding to > + * the already existing vma, vma_merge() will merge this extension with > + * the already existing vma (expand operation itself) and possibly also > + * with the next vma if it becomes adjacent to the expanded vma and > + * otherwise compatible. > + */ > + vma = vma_merge(mm, vma, extension_start, extension_end, > + vma->vm_flags, vma->anon_vma, vma->vm_file, > + extension_pgoff, vma_policy(vma), > + vma->vm_userfaultfd_ctx, anon_vma_name(vma)); > + if (!vma) { > vm_unacct_memory(pages); > ret = -ENOMEM; > goto out; > diff --git a/tools/testing/selftests/vm/mremap_test.c b/tools/testing/selftests/vm/mremap_test.c > index db0270127aeb..0865a6cb5bdb 100644 > --- a/tools/testing/selftests/vm/mremap_test.c > +++ b/tools/testing/selftests/vm/mremap_test.c > @@ -118,6 +118,48 @@ static unsigned long long get_mmap_min_addr(void) > return addr; > } > > +/* > + * This test validates that merge is called when expanding a mapping. > + * Mapping containing three pages is created, middle page is unmapped > + * and then the mapping containing the first page is expanded so that > + * it fills the created hole. The two parts should merge creating > + * single mapping with three pages. > + */ > +static void mremap_expand_merge(unsigned long page_size) > +{ > + char *test_name = "mremap expand merge"; > + FILE *fp; > + char *line = NULL; > + size_t len = 0; > + bool success = false; > + > + char *start = mmap(NULL, 3 * page_size, PROT_READ | PROT_WRITE, MAP_PRIVATE | MAP_ANONYMOUS, -1, 0); > + munmap(start + page_size, page_size); > + mremap(start, page_size, 2 * page_size, 0); > + > + fp = fopen("/proc/self/maps", "r"); > + if (fp == NULL) { > + ksft_test_result_fail("%s\n", test_name); > + return; > + } > + > + while(getline(&line, &len, fp) != -1) { > + char *first = strtok(line,"- "); > + void *first_val = (void *) strtol(first, NULL, 16); > + char *second = strtok(NULL,"- "); > + void *second_val = (void *) strtol(second, NULL, 16); > + if (first_val == start && second_val == start + 3 * page_size) { > + success = true; > + break; > + } > + } > + if (success) > + ksft_test_result_pass("%s\n", test_name); > + else > + ksft_test_result_fail("%s\n", test_name); > + fclose(fp); > +} > + > /* > * Returns the start address of the mapping on success, else returns > * NULL on failure. > @@ -336,6 +378,7 @@ int main(int argc, char **argv) > int i, run_perf_tests; > unsigned int threshold_mb = VALIDATION_DEFAULT_THRESHOLD; > unsigned int pattern_seed; > + int num_expand_tests = 1; > struct test test_cases[MAX_TEST]; > struct test perf_test_cases[MAX_PERF_TEST]; > int page_size; > @@ -407,12 +450,14 @@ int main(int argc, char **argv) > (threshold_mb * _1MB >= _1GB); > > ksft_set_plan(ARRAY_SIZE(test_cases) + (run_perf_tests ? > - ARRAY_SIZE(perf_test_cases) : 0)); > + ARRAY_SIZE(perf_test_cases) : 0) + num_expand_tests); > > for (i = 0; i < ARRAY_SIZE(test_cases); i++) > run_mremap_test_case(test_cases[i], &failures, threshold_mb, > pattern_seed); > > + mremap_expand_merge(page_size); > + > if (run_perf_tests) { > ksft_print_msg("\n%s\n", > "mremap HAVE_MOVE_PMD/PUD optimization time comparison for 1GB region:");
diff --git a/mm/mremap.c b/mm/mremap.c index 0b93fac76851..66970dcd636a 100644 --- a/mm/mremap.c +++ b/mm/mremap.c @@ -9,6 +9,7 @@ */ #include <linux/mm.h> +#include <linux/mm_inline.h> #include <linux/hugetlb.h> #include <linux/shm.h> #include <linux/ksm.h> @@ -23,6 +24,7 @@ #include <linux/mmu_notifier.h> #include <linux/uaccess.h> #include <linux/userfaultfd_k.h> +#include <linux/mempolicy.h> #include <asm/cacheflush.h> #include <asm/tlb.h> @@ -1014,6 +1016,9 @@ SYSCALL_DEFINE5(mremap, unsigned long, addr, unsigned long, old_len, /* can we just expand the current mapping? */ if (vma_expandable(vma, new_len - old_len)) { long pages = (new_len - old_len) >> PAGE_SHIFT; + unsigned long extension_start = addr + old_len; + unsigned long extension_end = addr + new_len; + pgoff_t extension_pgoff = vma->vm_pgoff + (old_len >> PAGE_SHIFT); if (vma->vm_flags & VM_ACCOUNT) { if (security_vm_enough_memory_mm(mm, pages)) { @@ -1022,8 +1027,18 @@ SYSCALL_DEFINE5(mremap, unsigned long, addr, unsigned long, old_len, } } - if (vma_adjust(vma, vma->vm_start, addr + new_len, - vma->vm_pgoff, NULL)) { + /* + * Function vma_merge() is called on the extension we are adding to + * the already existing vma, vma_merge() will merge this extension with + * the already existing vma (expand operation itself) and possibly also + * with the next vma if it becomes adjacent to the expanded vma and + * otherwise compatible. + */ + vma = vma_merge(mm, vma, extension_start, extension_end, + vma->vm_flags, vma->anon_vma, vma->vm_file, + extension_pgoff, vma_policy(vma), + vma->vm_userfaultfd_ctx, anon_vma_name(vma)); + if (!vma) { vm_unacct_memory(pages); ret = -ENOMEM; goto out; diff --git a/tools/testing/selftests/vm/mremap_test.c b/tools/testing/selftests/vm/mremap_test.c index db0270127aeb..0865a6cb5bdb 100644 --- a/tools/testing/selftests/vm/mremap_test.c +++ b/tools/testing/selftests/vm/mremap_test.c @@ -118,6 +118,48 @@ static unsigned long long get_mmap_min_addr(void) return addr; } +/* + * This test validates that merge is called when expanding a mapping. + * Mapping containing three pages is created, middle page is unmapped + * and then the mapping containing the first page is expanded so that + * it fills the created hole. The two parts should merge creating + * single mapping with three pages. + */ +static void mremap_expand_merge(unsigned long page_size) +{ + char *test_name = "mremap expand merge"; + FILE *fp; + char *line = NULL; + size_t len = 0; + bool success = false; + + char *start = mmap(NULL, 3 * page_size, PROT_READ | PROT_WRITE, MAP_PRIVATE | MAP_ANONYMOUS, -1, 0); + munmap(start + page_size, page_size); + mremap(start, page_size, 2 * page_size, 0); + + fp = fopen("/proc/self/maps", "r"); + if (fp == NULL) { + ksft_test_result_fail("%s\n", test_name); + return; + } + + while(getline(&line, &len, fp) != -1) { + char *first = strtok(line,"- "); + void *first_val = (void *) strtol(first, NULL, 16); + char *second = strtok(NULL,"- "); + void *second_val = (void *) strtol(second, NULL, 16); + if (first_val == start && second_val == start + 3 * page_size) { + success = true; + break; + } + } + if (success) + ksft_test_result_pass("%s\n", test_name); + else + ksft_test_result_fail("%s\n", test_name); + fclose(fp); +} + /* * Returns the start address of the mapping on success, else returns * NULL on failure. @@ -336,6 +378,7 @@ int main(int argc, char **argv) int i, run_perf_tests; unsigned int threshold_mb = VALIDATION_DEFAULT_THRESHOLD; unsigned int pattern_seed; + int num_expand_tests = 1; struct test test_cases[MAX_TEST]; struct test perf_test_cases[MAX_PERF_TEST]; int page_size; @@ -407,12 +450,14 @@ int main(int argc, char **argv) (threshold_mb * _1MB >= _1GB); ksft_set_plan(ARRAY_SIZE(test_cases) + (run_perf_tests ? - ARRAY_SIZE(perf_test_cases) : 0)); + ARRAY_SIZE(perf_test_cases) : 0) + num_expand_tests); for (i = 0; i < ARRAY_SIZE(test_cases); i++) run_mremap_test_case(test_cases[i], &failures, threshold_mb, pattern_seed); + mremap_expand_merge(page_size); + if (run_perf_tests) { ksft_print_msg("\n%s\n", "mremap HAVE_MOVE_PMD/PUD optimization time comparison for 1GB region:");
When mremap call results in expansion, it might be possible to merge the VMA with the next VMA which might become adjacent. This patch adds vma_merge call after the expansion is done to try and merge. Signed-off-by: Jakub Matěna <matenajakub@gmail.com> --- mm/mremap.c | 19 +++++++++- tools/testing/selftests/vm/mremap_test.c | 47 +++++++++++++++++++++++- 2 files changed, 63 insertions(+), 3 deletions(-)