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charset="us-ascii" Content-Disposition: inline On Thu, Feb 20, 2025 at 08:01:57PM +0900, Harry Yoo wrote: > On Thu, Feb 20, 2025 at 12:39:43PM +0900, Hyesoo Yu wrote: > > Previously, the restore occured after printing the object in slub. > > After commit 47d911b02cbe ("slab: make check_object() more consistent"), > > the bytes are printed after the restore. This information about the bytes > > before the restore is highly valuable for debugging purpose. > > For instance, in a event of cache issue, it displays byte patterns > > by breaking them down into 64-bytes units. Without this information, > > we can only speculate on how it was broken. Hence the corrupted regions > > should be printed prior to the restoration process. However if an object > > breaks in multiple places, the same log may be output multiple times. > > Therefore the slub log is reported only once to prevent redundant printing, > > by sending a parameter indicating whether an error has occurred previously. > > > > Changes in v3: > > - Change the parameter type of check_bytes_and_report. > > > > Changes in v2: > > - Instead of using print_section every time on check_bytes_and_report, > > just print it once for the entire slub object before the restore. > > > > Signed-off-by: Hyesoo Yu > > Change-Id: I73cf76c110eed62506643913517c957c05a29520 > > As previously mentioned by others, Change-Id is not used in Linux > kernel development. > Oops, It is my mistake. I will remove it. > > --- > > mm/slub.c | 29 ++++++++++++++--------------- > > 1 file changed, 14 insertions(+), 15 deletions(-) > > > > diff --git a/mm/slub.c b/mm/slub.c > > index b3969d63cc04..de62fed12236 100644 > > --- a/mm/slub.c > > +++ b/mm/slub.c > > @@ -1192,12 +1192,13 @@ static void restore_bytes(struct kmem_cache *s, char *message, u8 data, > > > > static pad_check_attributes int > > check_bytes_and_report(struct kmem_cache *s, struct slab *slab, > > - u8 *object, char *what, > > - u8 *start, unsigned int value, unsigned int bytes) > > + u8 *object, char *what, u8 *start, unsigned int value, > > + unsigned int bytes, bool slab_obj_print) > > { > > u8 *fault; > > u8 *end; > > u8 *addr = slab_address(slab); > > + char buf[100]; > > > > metadata_access_enable(); > > fault = memchr_inv(kasan_reset_tag(start), value, bytes); > > @@ -1212,11 +1213,14 @@ check_bytes_and_report(struct kmem_cache *s, struct slab *slab, > > if (slab_add_kunit_errors()) > > goto skip_bug_print; > > > > - slab_bug(s, "%s overwritten", what); > > pr_err("0x%p-0x%p @offset=%tu. First byte 0x%x instead of 0x%x\n", > > fault, end - 1, fault - addr, > > fault[0], value); > > > > + scnprintf(buf, 100, "%s overwritten", what); > > How about moving this into the if block and changing 100 to sizeof(buf)? > That sounds good. I will change it. > > + if (slab_obj_print) > > + object_err(s, slab, object, buf); > > + > > skip_bug_print: > > restore_bytes(s, what, value, fault, end); > > return 0; > > @@ -1279,7 +1283,7 @@ static int check_pad_bytes(struct kmem_cache *s, struct slab *slab, u8 *p) > > return 1; > > > > return check_bytes_and_report(s, slab, p, "Object padding", > > - p + off, POISON_INUSE, size_from_object(s) - off); > > + p + off, POISON_INUSE, size_from_object(s) - off, true); > > } > > > > /* Check the pad bytes at the end of a slab page */ > > @@ -1329,11 +1333,11 @@ static int check_object(struct kmem_cache *s, struct slab *slab, > > > > if (s->flags & SLAB_RED_ZONE) { > > if (!check_bytes_and_report(s, slab, object, "Left Redzone", > > - object - s->red_left_pad, val, s->red_left_pad)) > > + object - s->red_left_pad, val, s->red_left_pad, !!ret)) > > I think you don't have to add !! to ret. > Converting from int to _Bool is legal in C99 and it will work as intended. > Thank you for informing me. I remove !! to next version. Thanks, Regards. > > ret = 0; > > -- > Cheers, > Harry > ------2jehmUjxW0Gkbg46_GefLyBaSre4jpBnLPH4I-DC_hWbz.jz=_11514c_ Content-Type: text/plain; charset="utf-8" ------2jehmUjxW0Gkbg46_GefLyBaSre4jpBnLPH4I-DC_hWbz.jz=_11514c_--