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bh=1o61Qk94CL4mSIhccjHJY7EvYYVIe92QlAhm7buoWiM=; b=hoS6WzLX92siJQd58yX34F7ZE406MiHZUtJm7ZnTTXut0OPawaEB5OSTDQF94KhAJTLVd3 BGRdwFxo9ctXQxvlrI8/QjyIKfosAPi3jLuo3C7hFb1PGDdHG2Jx3k/gvnO/0yHOau46JL ImHUSExE53hTZx3l6wphOA+CVUG+oYI= ARC-Authentication-Results: i=1; imf28.hostedemail.com; dkim=none; dmarc=none; spf=pass (imf28.hostedemail.com: domain of rakie.kim@sk.com designates 166.125.252.92 as permitted sender) smtp.mailfrom=rakie.kim@sk.com X-AuditID: a67dfc5b-681ff7000002311f-6e-67ff61235ab6 From: Rakie Kim To: Honggyu Kim Cc: kernel_team@skhynix.com, akpm@linux-foundation.org, gourry@gourry.net, linux-mm@kvack.org, linux-kernel@vger.kernel.org, linux-cxl@vger.kernel.org, joshua.hahnjy@gmail.com, dan.j.williams@intel.com, ying.huang@linux.alibaba.com, david@redhat.com, osalvador@suse.de, yunjeong.mun@sk.com, Jonathan Cameron , Rakie Kim Subject: Re: [PATCH v7 3/3] mm/mempolicy: Support memory hotplug in weighted interleave Date: Wed, 16 Apr 2025 16:49:32 +0900 Message-ID: <20250416074951.610-1-rakie.kim@sk.com> X-Mailer: git-send-email 2.48.1.windows.1 In-Reply-To: <6a651c16-7ffc-42a5-8c98-95949073c804@sk.com> References: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Brightmail-Tracker: H4sIAAAAAAAAA+NgFnrOLMWRmVeSWpSXmKPExsXC9ZZnka5K4v90gxVXmC3mrF/DZjF96gVG i6/rfzFb/Lx7nN1i1cJrbBbHt85jtzg/6xSLxeVdc9gs7q35z2pxZlqRxeo1GQ7cHjtn3WX3 6G67zO7RcuQtq8fiPS+ZPDZ9msTucWLGbxaPnQ8tPd7vu8rmsfl0tcfnTXIBXFFcNimpOZll qUX6dglcGbOPTmApWO9T8eTZD6YGxquWXYycHBICJhJ9c94zdjFygNldP6VBTDYBJYlje2NA KkQEVCTWHpzC1sXIxcEs0MkssejoPmaQhLBAuMSfHzdZQWwWAVWJu53PGUFsXgFjifa/s1kh xmtKNFy6xwRicwpYSUx9eokNxBYS4JF4tWE/VL2gxMmZT1hAbGYBeYnmrbOZIXo/s0msuOgH YUtKHFxxg2UCI/8sJC2zkLQsYGRaxSiUmVeWm5iZY6KXUZmXWaGXnJ+7iREY/Mtq/0TvYPx0 IfgQowAHoxIPb0T8v3Qh1sSy4srcQ4wSHMxKIrznzIFCvCmJlVWpRfnxRaU5qcWHGKU5WJTE eY2+lacICaQnlqRmp6YWpBbBZJk4OKUaGNfcmlScz/7ed3+VaZdTRvqs/38a7peytl1VrTD3 K9D3vPtBNrwz/i77yUlmioc8Ni+PfsD0xpTzgC3XoosSpxSyJ+7zOnUj5xwv15f3qnPmrf4c Zvl/m2K2y4X/brP54uPCtwuX7vxaddp2ma3v5Kp7OULXCt4vf1O0KaLz+ebfO841azo9S1Bi Kc5INNRiLipOBAB+zyfyegIAAA== X-Brightmail-Tracker: H4sIAAAAAAAAA+NgFnrELMWRmVeSWpSXmKPExsXCNUNNS1c58X+6wZmjhhZz1q9hs5g+9QKj xdf1v5gtft49zm7x+dlrZotVC6+xWRzfOo/d4vDck6wW52edYrG4vGsOm8W9Nf9ZLc5MK7I4 dO05q8XqNRkWv7etYHPg99g56y67R3fbZXaPliNvWT0W73nJ5LHp0yR2jxMzfrN47Hxo6fF+ 31U2j2+3PTwWv/jA5LH5dLXH501yATxRXDYpqTmZZalF+nYJXBmzj05gKVjvU/Hk2Q+mBsar ll2MHBwSAiYSXT+lQUw2ASWJY3tjuhg5OUQEVCTWHpzC1sXIxcEs0MkssejoPmaQhLBAuMSf HzdZQWwWAVWJu53PGUFsXgFjifa/s8HiEgKaEg2X7jGB2JwCVhJTn15iA7GFBHgkXm3YD1Uv KHFy5hMWEJtZQF6ieets5gmMPLOQpGYhSS1gZFrFKJKZV5abmJljqlecnVGZl1mhl5yfu4kR GPLLav9M3MH45bL7IUYBDkYlHt6I+H/pQqyJZcWVuYcYJTiYlUR4z5kDhXhTEiurUovy44tK c1KLDzFKc7AoifN6hacmCAmkJ5akZqemFqQWwWSZODilGhj91t2f1d38faeZuc7ryperWXf4 fjRu7n961VEq+bF2fIfEPaEET9H5tj9nHS/mzTTzKa5/ef1S+qoVilpKLx3vvtp1nmuxYxaz +MIkhVXe9RJac2/VSvA7VfAm7e7anMLt4y9Sv9g51Euq8U2K1u9tFgsn10z+0i6+UmpP4b4K gfqTOh9EfJVYijMSDbWYi4oTAemx/8B1AgAA X-CFilter-Loop: Reflected X-Rspamd-Server: rspam06 X-Rspamd-Queue-Id: A5927C000A X-Stat-Signature: hq4xn7c33xzuabkp9sywufo5zbwqp6kz X-Rspam-User: X-HE-Tag: 1744789799-996325 X-HE-Meta: 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 Xug68OK/ hbf8DPaS8sY3UhCrewu2zlZ72iarNXGoSkFfFbbG9DJY1b73/DPrAo9oT41YjxNLPcAyweR28m/lgPJj2hLkk9e/7s0o4qhz1zJw4czZjrOO+NiUAuJMpxZCqfrh9PDpra6/P 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 Wed, 16 Apr 2025 13:04:32 +0900 Honggyu Kim wrote: Hi Jonathan and Honggyu, Thank you for reviewing this patch and for offering valuable ideas to address the issues. I have accepted all of your suggestions and am currently preparing a new patch series, version v8. > Hi Jonathan, > > Thanks for reviewing our patches. > > I have a few comments and the rest will be addressed by Rakie. > > On 4/16/2025 1:00 AM, Jonathan Cameron wrote: > > On Tue, 8 Apr 2025 16:32:42 +0900 > > Rakie Kim wrote: > > > >> @@ -3470,13 +3472,24 @@ static ssize_t node_store(struct kobject *kobj, struct kobj_attribute *attr, > >> > >> static void sysfs_wi_node_delete(int nid) > >> { > >> - if (!wi_group->nattrs[nid]) > >> + struct iw_node_attr *attr; > >> + > >> + if (nid < 0 || nid >= nr_node_ids) > >> + return; > >> + > >> + mutex_lock(&wi_group->kobj_lock); > >> + attr = wi_group->nattrs[nid]; > >> + if (!attr) { > >> + mutex_unlock(&wi_group->kobj_lock); > >> return; > >> + } > >> + > >> + wi_group->nattrs[nid] = NULL; > >> + mutex_unlock(&wi_group->kobj_lock); > >> > >> - sysfs_remove_file(&wi_group->wi_kobj, > >> - &wi_group->nattrs[nid]->kobj_attr.attr); > >> - kfree(wi_group->nattrs[nid]->kobj_attr.attr.name); > >> - kfree(wi_group->nattrs[nid]); > >> + sysfs_remove_file(&wi_group->wi_kobj, &attr->kobj_attr.attr); > >> + kfree(attr->kobj_attr.attr.name); > >> + kfree(attr); > > Here you go through a careful dance to not touch wi_group->nattrs[nid] > > except under the lock, but later you are happy to do so in the > > error handling paths. Maybe better to do similar to here and > > set it to NULL under the lock but do the freeing on a copy taken > > under that lock. I have updated the error handling path in sysfs_wi_node_add() as you suggested. > > . > >> } > >> > >> static void sysfs_wi_release(struct kobject *wi_kobj) > >> @@ -3495,35 +3508,77 @@ static const struct kobj_type wi_ktype = { > >> > >> static int sysfs_wi_node_add(int nid) > >> { > >> - struct iw_node_attr *node_attr; > >> + int ret = 0; > > > > Trivial but isn't ret always set when it is used? So no need to initialize > > here. In the updated code for v8, I retained the initialization of `ret = 0` because it is required for proper cleanup handling in the current version. > > If we don't initialize it, then this kind of trivial fixup might be needed later > so I think there is no reason not to initialize it. > https://lore.kernel.org/mm-commits/20240705010631.46743C4AF07@smtp.kernel.org > > > > >> char *name; > >> + struct iw_node_attr *new_attr = NULL; > > > > This is also always set before use so I'm not seeing a > > reason to initialize it to NULL. > > Ditto. I also removed the unnecessary `= NULL` initializer for `new_attr`, as it is always assigned before use. > > > > > > >> > >> - node_attr = kzalloc(sizeof(*node_attr), GFP_KERNEL); > >> - if (!node_attr) > >> + if (nid < 0 || nid >= nr_node_ids) { > >> + pr_err("Invalid node id: %d\n", nid); > >> + return -EINVAL; > >> + } > >> + > >> + new_attr = kzalloc(sizeof(struct iw_node_attr), GFP_KERNEL); > > > > I'd prefer sizeof(*new_attr) because I'm lazy and don't like checking > > types for allocation sizes :) Local style seems to be a bit > > of a mix though. > > Agreed. As you recommended, I changed the allocation from `sizeof(struct iw_node_attr)` to `sizeof(*new_attr)` for better readability and consistency. > > > > >> + if (!new_attr) > >> return -ENOMEM; > >> > >> name = kasprintf(GFP_KERNEL, "node%d", nid); > >> if (!name) { > >> - kfree(node_attr); > >> + kfree(new_attr); > >> return -ENOMEM; > >> } > >> > >> - sysfs_attr_init(&node_attr->kobj_attr.attr); > >> - node_attr->kobj_attr.attr.name = name; > >> - node_attr->kobj_attr.attr.mode = 0644; > >> - node_attr->kobj_attr.show = node_show; > >> - node_attr->kobj_attr.store = node_store; > >> - node_attr->nid = nid; > >> + mutex_lock(&wi_group->kobj_lock); > >> + if (wi_group->nattrs[nid]) { > >> + mutex_unlock(&wi_group->kobj_lock); > >> + pr_info("Node [%d] already exists\n", nid); > >> + kfree(new_attr); > >> + kfree(name); > >> + return 0; > >> + } > >> + wi_group->nattrs[nid] = new_attr; > > This set can be done after all the "wi_group->nattrs[nid]" related set is done. > > >> > >> - if (sysfs_create_file(&wi_group->wi_kobj, &node_attr->kobj_attr.attr)) { > >> - kfree(node_attr->kobj_attr.attr.name); > >> - kfree(node_attr); > >> - pr_err("failed to add attribute to weighted_interleave\n"); > >> - return -ENOMEM; > >> + sysfs_attr_init(&wi_group->nattrs[nid]->kobj_attr.attr); > > > > I'd have been tempted to use the new_attr pointer but perhaps > > this brings some documentation like advantages. > > +1 Additionally, I replaced all usage of `wi_group->nattrs[nid]` in sysfs_wi_node_add() with the `new_attr` pointer to simplify the logic and improve clarity. This also aligns with your suggestion to treat `new_attr` consistently throughout the function. > > > > >> + wi_group->nattrs[nid]->kobj_attr.attr.name = name; > >> + wi_group->nattrs[nid]->kobj_attr.attr.mode = 0644; > >> + wi_group->nattrs[nid]->kobj_attr.show = node_show; > >> + wi_group->nattrs[nid]->kobj_attr.store = node_store; > >> + wi_group->nattrs[nid]->nid = nid; > > As Jonathan mentioned, all the "wi_group->nattrs[nid]" here is better to be > "new_attr" for simplicity. > > Thanks, > Honggyu > > >> + > >> + ret = sysfs_create_file(&wi_group->wi_kobj, > >> + &wi_group->nattrs[nid]->kobj_attr.attr); > >> + if (ret) { > >> + kfree(wi_group->nattrs[nid]->kobj_attr.attr.name); > > > > See comment above on the rather different handling here to in > > sysfs_wi_node_delete() where you set it to NULL first, release the lock and tidy up. > > new_attrand name are still set so you could even combine the handling with the > > if (wi_group->nattrs[nid]) above via appropriate gotos. I agree with your observation regarding the difference in error handling between sysfs_wi_node_add() and sysfs_wi_node_delete(), so I refactored sysfs_wi_node_add() to follow the same structure. I will apply all of these updates in the new v8 series. Thank you again for your thoughtful and detailed feedback. Below is the revised code after incorporating your feedback. Rakie @@ -3532,14 +3532,14 @@ static int sysfs_wi_node_add(int nid) { int ret = 0; char *name; - struct iw_node_attr *new_attr = NULL; + struct iw_node_attr *new_attr; if (nid < 0 || nid >= nr_node_ids) { - pr_err("Invalid node id: %d\n", nid); + pr_err("invalid node id: %d\n", nid); return -EINVAL; } - new_attr = kzalloc(sizeof(struct iw_node_attr), GFP_KERNEL); + new_attr = kzalloc(sizeof(*new_attr), GFP_KERNEL); if (!new_attr) return -ENOMEM; @@ -3549,33 +3549,32 @@ static int sysfs_wi_node_add(int nid) return -ENOMEM; } + sysfs_attr_init(&new_attr->kobj_attr.attr); + new_attr->kobj_attr.attr.name = name; + new_attr->kobj_attr.attr.mode = 0644; + new_attr->kobj_attr.show = node_show; + new_attr->kobj_attr.store = node_store; + new_attr->nid = nid; + mutex_lock(&wi_group->kobj_lock); if (wi_group->nattrs[nid]) { mutex_unlock(&wi_group->kobj_lock); - pr_info("Node [%d] already exists\n", nid); - kfree(new_attr); - kfree(name); - return 0; + pr_info("node%d already exists\n", nid); + goto out; } - wi_group->nattrs[nid] = new_attr; - - sysfs_attr_init(&wi_group->nattrs[nid]->kobj_attr.attr); - pr_info("Node [%d] already exists\n", nid); - kfree(new_attr); - kfree(name); - return 0; + pr_info("node%d already exists\n", nid); + goto out; } - wi_group->nattrs[nid] = new_attr; - - sysfs_attr_init(&wi_group->nattrs[nid]->kobj_attr.attr); - wi_group->nattrs[nid]->kobj_attr.attr.name = name; - wi_group->nattrs[nid]->kobj_attr.attr.mode = 0644; - wi_group->nattrs[nid]->kobj_attr.show = node_show; - wi_group->nattrs[nid]->kobj_attr.store = node_store; - wi_group->nattrs[nid]->nid = nid; - ret = sysfs_create_file(&wi_group->wi_kobj, - &wi_group->nattrs[nid]->kobj_attr.attr); + ret = sysfs_create_file(&wi_group->wi_kobj, &new_attr->kobj_attr.attr); if (ret) { - kfree(wi_group->nattrs[nid]->kobj_attr.attr.name); - kfree(wi_group->nattrs[nid]); - wi_group->nattrs[nid] = NULL; - pr_err("Failed to add attribute to weighted_interleave: %d\n", ret); + mutex_unlock(&wi_group->kobj_lock); + goto out; } + wi_group->nattrs[nid] = new_attr; mutex_unlock(&wi_group->kobj_lock); + return 0; +out: + kfree(new_attr->kobj_attr.attr.name); + kfree(new_attr); return ret; } > > > >> + kfree(wi_group->nattrs[nid]); > >> + wi_group->nattrs[nid] = NULL; > >> + pr_err("Failed to add attribute to weighted_interleave: %d\n", ret); > >> } > >> + mutex_unlock(&wi_group->kobj_lock); > >> > >> - wi_group->nattrs[nid] = node_attr; > >> - return 0; > >> + return ret; > >> +} > > > >