Messages in this thread | | | From | weizhenliang <> | Subject | Re: [PATCH v2 1/2] tools/vm/page_owner_sort.c: Sort by stacktrace before culling | Date | Thu, 25 Nov 2021 09:46:41 +0000 |
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On 2021/11/25 3:37, Sean Anderson <seanga2@gmail.com> wrote:
> static int compare_num(const void *p1, const void *p2) @@ -121,6 >+122,7 @@ static void add_list(char *buf, int len) >list[list_size].page_num = get_page_num(buf); >memcpy(list[list_size].txt, buf, len); list[list_size].txt[len] = 0; >+ list[list_size].stacktrace = strchr(list[list_size].txt, '\n');
When read_block gets an empty line, buf is "\n", then the stacktrace is NULL
> list_size++; > if (list_size % 1000 == 0) { > printf("loaded %d\r", list_size); >@@ -199,7 +201,7 @@ int main(int argc, char **argv) > > printf("sorting ....\n"); > >- qsort(list, list_size, sizeof(list[0]), compare_txt); >+ qsort(list, list_size, sizeof(list[0]), compare_stacktrace); > > list2 = malloc(sizeof(*list) * list_size); if (!list2) { @@ -211,7 >+213,7 @@ int main(int argc, char **argv) > > for (i = count = 0; i < list_size; i++) { if (count == 0 || >- strcmp(list2[count-1].txt, list[i].txt) != 0) { >+ strcmp(list2[count-1].stacktrace, list[i].stacktrace) != 0) {
And when stacktrace is NULL, a segmentation fault will be triggered here.
> list2[count++] = list[i]; > } else { > list2[count-1].num += list[i].num;
1. Maybe you can check whether the ret of read_block is 0 before add_list, or whether the len of buf is 0 in add_list 2. Is it necessary to check stacktrace==NULL before use ?
Wei.
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