LKML Archive on lore.kernel.org
help / color / mirror / Atom feed
From: weizhenliang <weizhenliang@huawei.com>
To: Sean Anderson <seanga2@gmail.com>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	Andrew Morton <akpm@linux-foundation.org>
Cc: Changhee Han <ch0.han@lge.com>,
	Tang Bin <tangbin@cmss.chinamobile.com>,
	Zhang Shengju <zhangshengju@cmss.chinamobile.com>
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	[thread overview]
Message-ID: <22bad523dffb4681a201e6fedef7c50d@huawei.com> (raw)

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.

             reply	other threads:[~2021-11-25  9:48 UTC|newest]

Thread overview: 3+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-11-25  9:46 weizhenliang [this message]
2021-11-25 16:26 ` Sean Anderson
  -- strict thread matches above, loose matches on Subject: below --
2021-11-24 19:37 Sean Anderson

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=22bad523dffb4681a201e6fedef7c50d@huawei.com \
    --to=weizhenliang@huawei.com \
    --cc=akpm@linux-foundation.org \
    --cc=ch0.han@lge.com \
    --cc=linux-kernel@vger.kernel.org \
    --cc=seanga2@gmail.com \
    --cc=tangbin@cmss.chinamobile.com \
    --cc=zhangshengju@cmss.chinamobile.com \
    --subject='Re: [PATCH v2 1/2] tools/vm/page_owner_sort.c: Sort by stacktrace before culling' \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).