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charset="us-ascii" Content-Disposition: inline On Mon, Feb 24, 2025 at 03:08:55PM +0100, Vlastimil Babka wrote: > On 2/24/25 03:43, Hyesoo Yu wrote: > > On Fri, Feb 21, 2025 at 05:16:01PM +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 > >> > --- > >> > mm/slub.c | 29 ++++++++++++++--------------- > >> > 1 file changed, 14 insertions(+), 15 deletions(-) > >> > > >> > >> > @@ -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); > >> > + if (slab_obj_print) > >> > + object_err(s, slab, object, buf); > >> > >> > >> Wait, I think it's better to keep printing "%s overwritten" regardless > >> of slab_obj_print and only call __slab_err() if slab_obj_print == true > >> as discussed here [1]? Becuase in case there are multiple errors, > >> users should know. > >> > >> [1] https://lore.kernel.org/all/2ff52c5e-4b6b-4b3d-9047-f00967315d3e@suse.cz > >> > > > > Hi, > > > > __slab_err() doesn't include print_trainer(). It needs object_err(). > > print_trailer() could be used directly? > object_err calls print_trailer, add_taint and WARN_ON that we need to call here. I think direct calling is just redundant. > > How about including the specific error name 'what' to pr_err ? > > And then object_err would print "Object corrupt" at the beginning once > > without buf like below. > > Could also work. > > > if (slab_obj_print) > > object_err(s, slab, object, "Object corrupt"); > > > > pr_err("[%s] 0x%p-0x%p @offset=%tu. First byte 0x%x instead of 0x%x\n", > > what, fault, end - 1, fault - addr, fault[0], value); > > Probably in opposite order so object_err doesn't panic_on_warn before the > pr_err? > Yes, I tested and found that logs are not printed when panic_on_warn is enabled. we first call pr_err and then call object_err. > > Thanks, > > Regards. > >> -- > >> Cheers, > >> Harry > >> > > > > > > ------RdGIdtKpq9gE1V3j7PuPL63Cok.9YsQMFtrTWahmlx-pp0Iy=_139873_ Content-Type: text/plain; charset="utf-8" ------RdGIdtKpq9gE1V3j7PuPL63Cok.9YsQMFtrTWahmlx-pp0Iy=_139873_--