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Message-ID: <YCmAGNyFAOZs7GCG@zeniv-ca.linux.org.uk>
Date: Sun, 14 Feb 2021 19:55:04 +0000
From: Al Viro <viro@...iv.linux.org.uk>
To: Naresh Kamboju <naresh.kamboju@...aro.org>
Cc: Arnd Bergmann <arnd@...nel.org>,
open list <linux-kernel@...r.kernel.org>,
Linux-Next Mailing List <linux-next@...r.kernel.org>,
LTP List <ltp@...ts.linux.it>, lkft-triage@...ts.linaro.org,
chrubis <chrubis@...e.cz>, Jan Stancek <jstancek@...hat.com>,
Stephen Rothwell <sfr@...b.auug.org.au>,
Arnd Bergmann <arnd@...db.de>,
"Eric W. Biederman" <ebiederm@...ssion.com>,
Christian Brauner <christian@...uner.io>,
Kees Cook <keescook@...omium.org>,
Peter Xu <peterx@...hat.com>,
Andrew Morton <akpm@...ux-foundation.org>,
Petr Vorel <pvorel@...e.cz>,
Richard Palethorpe <rpalethorpe@...e.com>,
Joerg.Vehlow@...-tech.de
Subject: Re: LTP: madvise08.c:203: TFAIL: No sequence in dump after
MADV_DODUMP.
On Mon, Jan 25, 2021 at 10:01:48PM +0530, Naresh Kamboju wrote:
> commit 8a3cc755b13808eba74846dfd1033fcbc21f9a65
> Author: Al Viro <viro@...iv.linux.org.uk>
> Date: Sun Mar 8 09:16:37 2020 -0400
>
> coredump: don't bother with do_truncate()
>
> have dump_skip() just remember how much needs to be skipped,
> leave actual seeks/writing zeroes to the next dump_emit()
> or the end of coredump output, whichever comes first.
> And instead of playing with do_truncate() in the end, just
> write one NUL at the end of the last gap (if any).
>
> Signed-off-by: Al Viro <viro@...iv.linux.org.uk>
>
> fs/binfmt_elf.c | 1 -
> fs/coredump.c | 56 +++++++++++++++++++++++++++---------------------
> include/linux/binfmts.h | 1 +
> include/linux/coredump.h | 1 -
>
>
> Test case output link,
> https://lkft.validation.linaro.org/scheduler/job/2184975#L1369
> https://lkft.validation.linaro.org/scheduler/job/2184972#L1358
I think I see what's going on. Could you check if the following
fixes your reproducer?
diff --git a/arch/powerpc/platforms/cell/spufs/coredump.c b/arch/powerpc/platforms/cell/spufs/coredump.c
index 60b5583e9eaf..1a587618015c 100644
--- a/arch/powerpc/platforms/cell/spufs/coredump.c
+++ b/arch/powerpc/platforms/cell/spufs/coredump.c
@@ -149,8 +149,7 @@ static int spufs_arch_write_note(struct spu_context *ctx, int i,
return -EIO;
}
- if (!dump_skip(cprm, roundup(cprm->pos - ret + sz, 4) - cprm->pos))
- return -EIO;
+ dump_skip_to(cprm, roundup(cprm->pos - ret + sz, 4));
return 0;
}
diff --git a/fs/binfmt_elf.c b/fs/binfmt_elf.c
index 66137d5dca5f..474a3c7dd5ce 100644
--- a/fs/binfmt_elf.c
+++ b/fs/binfmt_elf.c
@@ -2267,8 +2267,7 @@ static int elf_core_dump(struct coredump_params *cprm)
goto end_coredump;
/* Align to page */
- if (!dump_skip(cprm, dataoff - cprm->pos))
- goto end_coredump;
+ dump_skip_to(cprm, dataoff);
for (i = 0; i < vma_count; i++) {
struct core_vma_metadata *meta = vma_meta + i;
diff --git a/fs/binfmt_elf_fdpic.c b/fs/binfmt_elf_fdpic.c
index be4062b8ba75..01f043971644 100644
--- a/fs/binfmt_elf_fdpic.c
+++ b/fs/binfmt_elf_fdpic.c
@@ -1640,8 +1640,7 @@ static int elf_fdpic_core_dump(struct coredump_params *cprm)
goto end_coredump;
}
- if (!dump_skip(cprm, dataoff - cprm->pos))
- goto end_coredump;
+ dump_skip_to(cprm, dataoff);
if (!elf_fdpic_dump_segments(cprm, vma_meta, vma_count))
goto end_coredump;
diff --git a/fs/coredump.c b/fs/coredump.c
index 27a93f724251..bfac7422cd14 100644
--- a/fs/coredump.c
+++ b/fs/coredump.c
@@ -894,7 +894,14 @@ int dump_emit(struct coredump_params *cprm, const void *addr, int nr)
}
EXPORT_SYMBOL(dump_emit);
-int dump_skip(struct coredump_params *cprm, size_t nr)
+void dump_skip_to(struct coredump_params *cprm, unsigned long pos)
+{
+ cprm->to_skip = pos - cprm->pos;
+ return 0;
+}
+EXPORT_SYMBOL(dump_skip_to);
+
+void dump_skip(struct coredump_params *cprm, size_t nr)
{
cprm->to_skip += nr;
return 0;
@@ -925,11 +932,11 @@ int dump_user_range(struct coredump_params *cprm, unsigned long start,
stop = !dump_emit(cprm, kaddr, PAGE_SIZE);
kunmap(page);
put_page(page);
+ if (stop)
+ return 0;
} else {
- stop = !dump_skip(cprm, PAGE_SIZE);
+ dump_skip(cprm, PAGE_SIZE);
}
- if (stop)
- return 0;
}
return 1;
}
@@ -940,7 +947,9 @@ int dump_align(struct coredump_params *cprm, int align)
unsigned mod = (cprm->pos + cprm->to_skip) & (align - 1);
if (align & (align - 1))
return 0;
- return mod ? dump_skip(cprm, align - mod) : 1;
+ if (mod)
+ cprm->to_skip += align - mod;
+ return 1;
}
EXPORT_SYMBOL(dump_align);
diff --git a/include/linux/coredump.h b/include/linux/coredump.h
index 806d7f87d16a..78fcd776b185 100644
--- a/include/linux/coredump.h
+++ b/include/linux/coredump.h
@@ -23,7 +23,8 @@ extern unsigned int core_pipe_limit;
* functions to write out all the necessary info.
*/
struct coredump_params;
-extern int dump_skip(struct coredump_params *cprm, size_t nr);
+extern void dump_skip_to(struct coredump_params *cprm, unsigned long to);
+extern void dump_skip(struct coredump_params *cprm, size_t nr);
extern int dump_emit(struct coredump_params *cprm, const void *addr, int nr);
extern int dump_align(struct coredump_params *cprm, int align);
int dump_user_range(struct coredump_params *cprm, unsigned long start,
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