On Mon, Jan 25, 2021 at 10:01:48PM +0530, Naresh Kamboju wrote:
commit 8a3cc755b13808eba74846dfd1033fcbc21f9a65 Author: Al Viro viro@zeniv.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@zeniv.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,