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Content-Language: en-US To: Hyesoo Yu Cc: janghyuck.kim@samsung.com, chengming.zhou@linux.dev, Christoph Lameter , Pekka Enberg , David Rientjes , Joonsoo Kim , Andrew Morton , Roman Gushchin , Hyeonggon Yoo <42.hyeyoo@gmail.com>, linux-mm@kvack.org, linux-kernel@vger.kernel.org References: <20250205004424.1214826-1-hyesoo.yu@samsung.com> From: Vlastimil Babka Autocrypt: addr=vbabka@suse.cz; keydata= xsFNBFZdmxYBEADsw/SiUSjB0dM+vSh95UkgcHjzEVBlby/Fg+g42O7LAEkCYXi/vvq31JTB KxRWDHX0R2tgpFDXHnzZcQywawu8eSq0LxzxFNYMvtB7sV1pxYwej2qx9B75qW2plBs+7+YB 87tMFA+u+L4Z5xAzIimfLD5EKC56kJ1CsXlM8S/LHcmdD9Ctkn3trYDNnat0eoAcfPIP2OZ+ 9oe9IF/R28zmh0ifLXyJQQz5ofdj4bPf8ecEW0rhcqHfTD8k4yK0xxt3xW+6Exqp9n9bydiy tcSAw/TahjW6yrA+6JhSBv1v2tIm+itQc073zjSX8OFL51qQVzRFr7H2UQG33lw2QrvHRXqD Ot7ViKam7v0Ho9wEWiQOOZlHItOOXFphWb2yq3nzrKe45oWoSgkxKb97MVsQ+q2SYjJRBBH4 8qKhphADYxkIP6yut/eaj9ImvRUZZRi0DTc8xfnvHGTjKbJzC2xpFcY0DQbZzuwsIZ8OPJCc LM4S7mT25NE5kUTG/TKQCk922vRdGVMoLA7dIQrgXnRXtyT61sg8PG4wcfOnuWf8577aXP1x 6mzw3/jh3F+oSBHb/GcLC7mvWreJifUL2gEdssGfXhGWBo6zLS3qhgtwjay0Jl+kza1lo+Cv BB2T79D4WGdDuVa4eOrQ02TxqGN7G0Biz5ZLRSFzQSQwLn8fbwARAQABzSBWbGFzdGltaWwg QmFia2EgPHZiYWJrYUBzdXNlLmN6PsLBlAQTAQoAPgIbAwULCQgHAwUVCgkICwUWAgMBAAIe AQIXgBYhBKlA1DSZLC6OmRA9UCJPp+fMgqZkBQJkBREIBQkRadznAAoJECJPp+fMgqZkNxIQ ALZRqwdUGzqL2aeSavbum/VF/+td+nZfuH0xeWiO2w8mG0+nPd5j9ujYeHcUP1edE7uQrjOC Gs9sm8+W1xYnbClMJTsXiAV88D2btFUdU1mCXURAL9wWZ8Jsmz5ZH2V6AUszvNezsS/VIT87 AmTtj31TLDGwdxaZTSYLwAOOOtyqafOEq+gJB30RxTRE3h3G1zpO7OM9K6ysLdAlwAGYWgJJ V4JqGsQ/lyEtxxFpUCjb5Pztp7cQxhlkil0oBYHkudiG8j1U3DG8iC6rnB4yJaLphKx57NuQ PIY0Bccg+r9gIQ4XeSK2PQhdXdy3UWBr913ZQ9AI2usid3s5vabo4iBvpJNFLgUmxFnr73SJ KsRh/2OBsg1XXF/wRQGBO9vRuJUAbnaIVcmGOUogdBVS9Sun/Sy4GNA++KtFZK95U7J417/J Hub2xV6Ehc7UGW6fIvIQmzJ3zaTEfuriU1P8ayfddrAgZb25JnOW7L1zdYL8rXiezOyYZ8Fm ZyXjzWdO0RpxcUEp6GsJr11Bc4F3aae9OZtwtLL/jxc7y6pUugB00PodgnQ6CMcfR/HjXlae h2VS3zl9+tQWHu6s1R58t5BuMS2FNA58wU/IazImc/ZQA+slDBfhRDGYlExjg19UXWe/gMcl De3P1kxYPgZdGE2eZpRLIbt+rYnqQKy8UxlszsBNBFsZNTUBCACfQfpSsWJZyi+SHoRdVyX5 J6rI7okc4+b571a7RXD5UhS9dlVRVVAtrU9ANSLqPTQKGVxHrqD39XSw8hxK61pw8p90pg4G /N3iuWEvyt+t0SxDDkClnGsDyRhlUyEWYFEoBrrCizbmahOUwqkJbNMfzj5Y7n7OIJOxNRkB IBOjPdF26dMP69BwePQao1M8Acrrex9sAHYjQGyVmReRjVEtv9iG4DoTsnIR3amKVk6si4Ea X/mrapJqSCcBUVYUFH8M7bsm4CSxier5ofy8jTEa/CfvkqpKThTMCQPNZKY7hke5qEq1CBk2 wxhX48ZrJEFf1v3NuV3OimgsF2odzieNABEBAAHCwXwEGAEKACYCGwwWIQSpQNQ0mSwujpkQ PVAiT6fnzIKmZAUCZAUSmwUJDK5EZgAKCRAiT6fnzIKmZOJGEACOKABgo9wJXsbWhGWYO7mD 8R8mUyJHqbvaz+yTLnvRwfe/VwafFfDMx5GYVYzMY9TWpA8psFTKTUIIQmx2scYsRBUwm5VI EurRWKqENcDRjyo+ol59j0FViYysjQQeobXBDDE31t5SBg++veI6tXfpco/UiKEsDswL1WAr tEAZaruo7254TyH+gydURl2wJuzo/aZ7Y7PpqaODbYv727Dvm5eX64HCyyAH0s6sOCyGF5/p eIhrOn24oBf67KtdAN3H9JoFNUVTYJc1VJU3R1JtVdgwEdr+NEciEfYl0O19VpLE/PZxP4wX PWnhf5WjdoNI1Xec+RcJ5p/pSel0jnvBX8L2cmniYnmI883NhtGZsEWj++wyKiS4NranDFlA HdDM3b4lUth1pTtABKQ1YuTvehj7EfoWD3bv9kuGZGPrAeFNiHPdOT7DaXKeHpW9homgtBxj 8aX/UkSvEGJKUEbFL9cVa5tzyialGkSiZJNkWgeHe+jEcfRT6pJZOJidSCdzvJpbdJmm+eED w9XOLH1IIWh7RURU7G1iOfEfmImFeC3cbbS73LQEFGe1urxvIH5K/7vX+FkNcr9ujwWuPE9b 1C2o4i/yZPLXIVy387EjA6GZMqvQUFuSTs/GeBcv0NjIQi8867H3uLjz+mQy63fAitsDwLmR EP+ylKVEKb0Q2A== In-Reply-To: <20250205004424.1214826-1-hyesoo.yu@samsung.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Rspamd-Action: no action X-Stat-Signature: founyuex7qm4yy6o1faoesyiz95ynrqj X-Rspamd-Queue-Id: E3408100022 X-Rspam-User: X-Rspamd-Server: rspam06 X-HE-Tag: 1738850935-405609 X-HE-Meta: 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 x/g/TrzC 4qRGTSZd//9KusCPIUaCT76cd2OpjBj91tShz X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 2/5/25 01:44, 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 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 > --- > mm/slub.c | 25 ++++++++++++------------- > 1 file changed, 12 insertions(+), 13 deletions(-) > > diff --git a/mm/slub.c b/mm/slub.c > index ea956cb4b8be..7a9f7a2c17d7 100644 > --- a/mm/slub.c > +++ b/mm/slub.c > @@ -1182,7 +1182,7 @@ 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 *start, unsigned int value, unsigned int bytes, int slab_obj_print) It would be better to redistribute the arguments among lines to fit each <80 chars. The previous line is underutilized. Also could the new argument be bool? > { > u8 *fault; > u8 *end; > @@ -1205,6 +1205,10 @@ check_bytes_and_report(struct kmem_cache *s, struct slab *slab, > 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); Hm we have slab_bug() above this, not slab_err(). So this is another place that would need to take care a WARN is called with your other patch. > + if (slab_obj_print) { > + print_trailer(s, slab, object); > + add_taint(TAINT_BAD_PAGE, LOCKDEP_NOW_UNRELIABLE); I guess we could do the WARN here. If panic_on_warn is enabled it will not report all problems that check_object() could find and panic on the first one. But that would have happened too with your slab_fix() approach (slab_fix() called from restore_bytes() below). I think we can live with that instead of needing two separate reporting and fixing rounds from check_object(). Could you send the two patches as a series in v3, as they are inter-dependent? Thanks. > + } > > skip_bug_print: > restore_bytes(s, what, value, fault, end); > @@ -1268,7 +1272,7 @@ 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, 1); > } > > /* Check the pad bytes at the end of a slab page */ > @@ -1318,11 +1322,11 @@ 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)) > ret = 0; > > if (!check_bytes_and_report(s, slab, object, "Right Redzone", > - endobject, val, s->inuse - s->object_size)) > + endobject, val, s->inuse - s->object_size, ret)) > ret = 0; > > if (slub_debug_orig_size(s) && val == SLUB_RED_ACTIVE) { > @@ -1331,7 +1335,7 @@ static int check_object(struct kmem_cache *s, struct slab *slab, > if (s->object_size > orig_size && > !check_bytes_and_report(s, slab, object, > "kmalloc Redzone", p + orig_size, > - val, s->object_size - orig_size)) { > + val, s->object_size - orig_size, ret)) { > ret = 0; > } > } > @@ -1339,7 +1343,7 @@ static int check_object(struct kmem_cache *s, struct slab *slab, > if ((s->flags & SLAB_POISON) && s->object_size < s->inuse) { > if (!check_bytes_and_report(s, slab, p, "Alignment padding", > endobject, POISON_INUSE, > - s->inuse - s->object_size)) > + s->inuse - s->object_size, ret)) > ret = 0; > } > } > @@ -1355,11 +1359,11 @@ static int check_object(struct kmem_cache *s, struct slab *slab, > if (kasan_meta_size < s->object_size - 1 && > !check_bytes_and_report(s, slab, p, "Poison", > p + kasan_meta_size, POISON_FREE, > - s->object_size - kasan_meta_size - 1)) > + s->object_size - kasan_meta_size - 1, ret)) > ret = 0; > if (kasan_meta_size < s->object_size && > !check_bytes_and_report(s, slab, p, "End Poison", > - p + s->object_size - 1, POISON_END, 1)) > + p + s->object_size - 1, POISON_END, 1, ret)) > ret = 0; > } > /* > @@ -1385,11 +1389,6 @@ static int check_object(struct kmem_cache *s, struct slab *slab, > ret = 0; > } > > - if (!ret && !slab_in_kunit_test()) { > - print_trailer(s, slab, object); > - add_taint(TAINT_BAD_PAGE, LOCKDEP_NOW_UNRELIABLE); > - } > - > return ret; > } >