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X-MS-Exchange-CrossTenant-FromEntityHeader: Hosted X-MS-Exchange-CrossTenant-Id: 4e2c6054-71cb-48f1-bd6c-3a9705aca71b X-MS-Exchange-CrossTenant-MailboxType: HOSTED X-MS-Exchange-CrossTenant-UserPrincipalName: 5gBEyEdaJjFzD87UNb+iblPObcIkeusvF3Qnv33gVBEO/PAw/GtOlBMJLvPl+HwdKSn5OmWijz8AQvr/9xmdMA== X-MS-Exchange-Transport-CrossTenantHeadersStamped: IA1PR10MB5993 X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1143,Hydra:6.1.51,FMLib:17.12.100.49 definitions=2026-03-11_02,2026-03-09_02,2025-10-01_01 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 bulkscore=0 mlxlogscore=871 adultscore=0 suspectscore=0 phishscore=0 malwarescore=0 spamscore=0 mlxscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2603050001 definitions=main-2603120025 X-Proofpoint-GUID: rVKrCakWV3ZKIzcoSWAQp6MMOhuJSyPX X-Authority-Analysis: v=2.4 cv=ZdsQ98VA c=1 sm=1 tr=0 ts=69b23302 cx=c_pps a=OOZaFjgC48PWsiFpTAqLcw==:117 a=OOZaFjgC48PWsiFpTAqLcw==:17 a=6eWqkTHjU83fiwn7nKZWdM+Sl24=:19 a=z/mQ4Ysz8XfWz/Q5cLBRGdckG28=:19 a=lCpzRmAYbLLaTzLvsPZ7Mbvzbb8=:19 a=xqWC_Br6kY4A:10 a=kj9zAlcOel0A:10 a=Yq5XynenixoA:10 a=GoEa3M9JfhUA:10 a=VkNPw1HP01LnGYTKEx00:22 a=jiCTI4zE5U7BLdzWsZGv:22 a=3I1J8UUJPc9JN9BFgKH3:22 a=VwQbUJbxAAAA:8 a=pGLkceISAAAA:8 a=I-ef4aZAHlghwQ6S9DkA:9 a=CjuIK1q_8ugA:10 X-Proofpoint-ORIG-GUID: rVKrCakWV3ZKIzcoSWAQp6MMOhuJSyPX X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwMzEyMDAyNSBTYWx0ZWRfXzpAY2BjPXhqd jBHYOH+f2n6FgZFVDGbbRrO4VaLf80EQC8GUj5NtoGIAG2EnnSf+bGycqO+ESkh8JvPHcUewgaF jmlv+6pKYu+kAkq/8hKBu+mN4XuhqFhcEItXcTP4IfRwSaalU0/cP68Mrv+mWREmUyJBx+yfJ5u b7oxSYsRJiSLYxB4eYf14Uw+Fexv+lzILdWNr+akusoNZkHQ9q/RX1tzUWgDBgUMWjM0fRY+nY9 sEn4RCjB1cj4viFEGe6tB4c6g7TZLVgv2xQWSWp6fPx5trnQGosXcUGD4KDlNvWYDV/E13bLhB/ nnT/LyqKTAIvZToFt4W3bX5kLTjndgGchRMeFLczr2qcuOeaAR71+IHvcsx4z5wBr8YhF4uhIlx BqUlHDW707xSaa+Omv4X6Y4rZHaQJQ2D9oGA4HwsCzOoo7rh+YG/0uJtAEanURj7fUcRXZXPxr3 6/llq+u6c3PYTnVF9Kw== On Wed, Mar 11, 2026 at 05:59:03PM +0100, Vlastimil Babka wrote: > On 3/11/26 12:16, Harry Yoo wrote: > > On Wed, Mar 11, 2026 at 05:36:17PM +0800, Qing Wang wrote: > >> When refill_sheaf() partially fills one sheaf (e.g., fills 5 objects > >> but need to fill 10), it will update sheaf->size and return -ENOMEM. > >> However, the callers (alloc_full_sheaf() and __pcs_replace_empty_main()) > >> directly call free_empty_sheaf() on failure, which only does kfree(sheaf), > >> causing the partially allocated objects memory in sheaf->objects[] leaked. > > > > Nice catch, thanks! > > Indeed, thanks! > > > Probably the need to fail new_slab() made it quite hard to trigger and notice. > > Agreed. > > >> Fix this by calling sheaf_flush_unused() before free_empty_sheaf() to > >> free objects of sheaf->objects[]. And also add a WARN_ON() in > >> free_empty_sheaf() to catch any future cases where a non-empty sheaf is > >> being freed. > >> > >> Fixes: 2d517aa09bbc ("slab: add opt-in caching layer of percpu sheaves") > > Actually I think that commit was fine as it was using bulk alloc to refill > and that was undoing any partial successes. I think this one is correct and > replaced it so: Oops, I missed that. Yeah, at first look I wondered "Well, refill_sheaf()" doesn't partially fill sheaves!" Then I looked at the code right now and it did :/ In 2d517aa09bbc did not partially refill sheaves as it used __kmem_cache_alloc_bulk() to refill sheaves, > Fixes: ed30c4adfc2b ("slab: add optimized sheaf refill from partial list") and this changed the behavior by replacing it with __refill_objects(). So this is the right Fixes: tag. > > I think we need to add Cc: stable@vger.kernel.org > > And therefore we don't, unless I'm mistaken. You're right. > >> Signed-off-by: Qing Wang > >> --- > >> mm/slub.c | 4 ++++ > >> 1 file changed, 4 insertions(+) > >> > >> diff --git a/mm/slub.c b/mm/slub.c > >> index 20cb4f3b636d..73b2cfd0e123 100644 > >> --- a/mm/slub.c > >> +++ b/mm/slub.c > >> @@ -2797,6 +2797,7 @@ static void free_empty_sheaf(struct kmem_cache *s, struct slab_sheaf *sheaf) > >> if (s->flags & SLAB_KMALLOC) > >> mark_obj_codetag_empty(sheaf); > >> > >> + WARN_ON(sheaf->size > 0); > > > > nit: perhaps VM_WARN_ON_ONCE(); will be enough? > > Yep replaced it too. > > Added to slab/for-next-fixes, thanks! -- Cheers, Harry / Hyeonggon