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[PATCH net v3] net: macb: Relocate mog_init_rings() callback from macb_mac_link_up() to macb_open()

by Xiaolei Wang

In the non-RT kernel, local_bh_disable() merely disables preemption, whereas it maps to an actual spin lock in the RT kernel. Consequently, when attempting to refill RX buffers via netdev_alloc_skb() in macb_mac_link_up(), a deadlock scenario arises as follows: WARNING: possible circular locking dependency detected 6.18.0-08691-g2061f18ad76e #39 Not tainted ------------------------------------------------------ kworker/0:0/8 is trying to acquire lock: ffff00080369bbe0 (&bp->lock){+.+.}-{3:3}, at: macb_start_xmit+0x808/0xb7c but task is already holding lock: ffff000803698e58 (&queue->tx_ptr_lock){+...}-{3:3}, at: macb_start_xmit +0x148/0xb7c which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #3 (&queue->tx_ptr_lock){+...}-{3:3}: rt_spin_lock+0x50/0x1f0 macb_start_xmit+0x148/0xb7c dev_hard_start_xmit+0x94/0x284 sch_direct_xmit+0x8c/0x37c __dev_queue_xmit+0x708/0x1120 neigh_resolve_output+0x148/0x28c ip6_finish_output2+0x2c0/0xb2c __ip6_finish_output+0x114/0x308 ip6_output+0xc4/0x4a4 mld_sendpack+0x220/0x68c mld_ifc_work+0x2a8/0x4f4 process_one_work+0x20c/0x5f8 worker_thread+0x1b0/0x35c kthread+0x144/0x200 ret_from_fork+0x10/0x20 -> #2 (_xmit_ETHER#2){+...}-{3:3}: rt_spin_lock+0x50/0x1f0 sch_direct_xmit+0x11c/0x37c __dev_queue_xmit+0x708/0x1120 neigh_resolve_output+0x148/0x28c ip6_finish_output2+0x2c0/0xb2c __ip6_finish_output+0x114/0x308 ip6_output+0xc4/0x4a4 mld_sendpack+0x220/0x68c mld_ifc_work+0x2a8/0x4f4 process_one_work+0x20c/0x5f8 worker_thread+0x1b0/0x35c kthread+0x144/0x200 ret_from_fork+0x10/0x20 -> #1 ((softirq_ctrl.lock)){+.+.}-{3:3}: lock_release+0x250/0x348 __local_bh_enable_ip+0x7c/0x240 __netdev_alloc_skb+0x1b4/0x1d8 gem_rx_refill+0xdc/0x240 gem_init_rings+0xb4/0x108 macb_mac_link_up+0x9c/0x2b4 phylink_resolve+0x170/0x614 process_one_work+0x20c/0x5f8 worker_thread+0x1b0/0x35c kthread+0x144/0x200 ret_from_fork+0x10/0x20 -> #0 (&bp->lock){+.+.}-{3:3}: __lock_acquire+0x15a8/0x2084 lock_acquire+0x1cc/0x350 rt_spin_lock+0x50/0x1f0 macb_start_xmit+0x808/0xb7c dev_hard_start_xmit+0x94/0x284 sch_direct_xmit+0x8c/0x37c __dev_queue_xmit+0x708/0x1120 neigh_resolve_output+0x148/0x28c ip6_finish_output2+0x2c0/0xb2c __ip6_finish_output+0x114/0x308 ip6_output+0xc4/0x4a4 mld_sendpack+0x220/0x68c mld_ifc_work+0x2a8/0x4f4 process_one_work+0x20c/0x5f8 worker_thread+0x1b0/0x35c kthread+0x144/0x200 ret_from_fork+0x10/0x20 other info that might help us debug this: Chain exists of: &bp->lock --> _xmit_ETHER#2 --> &queue->tx_ptr_lock Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(&queue->tx_ptr_lock); lock(_xmit_ETHER#2); lock(&queue->tx_ptr_lock); lock(&bp->lock); *** DEADLOCK *** Call trace: show_stack+0x18/0x24 (C) dump_stack_lvl+0xa0/0xf0 dump_stack+0x18/0x24 print_circular_bug+0x28c/0x370 check_noncircular+0x198/0x1ac __lock_acquire+0x15a8/0x2084 lock_acquire+0x1cc/0x350 rt_spin_lock+0x50/0x1f0 macb_start_xmit+0x808/0xb7c dev_hard_start_xmit+0x94/0x284 sch_direct_xmit+0x8c/0x37c __dev_queue_xmit+0x708/0x1120 neigh_resolve_output+0x148/0x28c ip6_finish_output2+0x2c0/0xb2c __ip6_finish_output+0x114/0x308 ip6_output+0xc4/0x4a4 mld_sendpack+0x220/0x68c mld_ifc_work+0x2a8/0x4f4 process_one_work+0x20c/0x5f8 worker_thread+0x1b0/0x35c kthread+0x144/0x200 ret_from_fork+0x10/0x20 Notably, invoking the mog_init_rings() callback upon link establishment is unnecessary. Instead, we can exclusively call mog_init_rings() within the ndo_open() callback. This adjustment resolves the deadlock issue. Furthermore, since MACB_CAPS_MACB_IS_EMAC cases do not use mog_init_rings() when opening the network interface via at91ether_open(), moving mog_init_rings() to macb_open() also eliminates the MACB_CAPS_MACB_IS_EMAC check. Fixes: 633e98a711ac ("net: macb: use resolved link config in mac_link_up()") Cc: stable(a)vger.kernel.org Suggested-by: Kevin Hao <kexin.hao(a)windriver.com> Signed-off-by: Xiaolei Wang <xiaolei.wang(a)windriver.com> --- V1: https://patchwork.kernel.org/project/netdevbpf/patch/20251128103647.351259-… V2: Update the correct lock dependency chain and add the Fix tag. V3: update commit log, Add full deadlock log added explanations: because MACB_CAPS_MACB_IS_EMAC cases do not use mog_init_rings(), we don't need the MACB_CAPS_MACB_IS_EMAC check when moving mog_init_rings() to macb_open(). drivers/net/ethernet/cadence/macb_main.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/drivers/net/ethernet/cadence/macb_main.c b/drivers/net/ethernet/cadence/macb_main.c index ca2386b83473..064fccdcf699 100644 --- a/drivers/net/ethernet/cadence/macb_main.c +++ b/drivers/net/ethernet/cadence/macb_main.c @@ -744,7 +744,6 @@ static void macb_mac_link_up(struct phylink_config *config, /* Initialize rings & buffers as clearing MACB_BIT(TE) in link down * cleared the pipeline and control registers. */ - bp->macbgem_ops.mog_init_rings(bp); macb_init_buffers(bp); for (q = 0, queue = bp->queues; q < bp->num_queues; ++q, ++queue) @@ -2991,6 +2990,8 @@ static int macb_open(struct net_device *dev) goto pm_exit; } + bp->macbgem_ops.mog_init_rings(bp); + for (q = 0, queue = bp->queues; q < bp->num_queues; ++q, ++queue) { napi_enable(&queue->napi_rx); napi_enable(&queue->napi_tx); -- 2.43.0

1 week

[PATCH v2 1/6] Revert "PCI: dw-rockchip: Don't wait for link since we can detect Link Up"

by Niklas Cassel

This reverts commit ec9fd499b9c60a187ac8d6414c3c343c77d32e42. While this fake hotplugging was a nice idea, it has shown that this feature does not handle PCIe switches correctly: pci_bus 0004:43: busn_res: can not insert [bus 43-41] under [bus 42-41] (conflicts with (null) [bus 42-41]) pci_bus 0004:43: busn_res: [bus 43-41] end is updated to 43 pci_bus 0004:43: busn_res: can not insert [bus 43] under [bus 42-41] (conflicts with (null) [bus 42-41]) pci 0004:42:00.0: devices behind bridge are unusable because [bus 43] cannot be assigned for them pci_bus 0004:44: busn_res: can not insert [bus 44-41] under [bus 42-41] (conflicts with (null) [bus 42-41]) pci_bus 0004:44: busn_res: [bus 44-41] end is updated to 44 pci_bus 0004:44: busn_res: can not insert [bus 44] under [bus 42-41] (conflicts with (null) [bus 42-41]) pci 0004:42:02.0: devices behind bridge are unusable because [bus 44] cannot be assigned for them pci_bus 0004:45: busn_res: can not insert [bus 45-41] under [bus 42-41] (conflicts with (null) [bus 42-41]) pci_bus 0004:45: busn_res: [bus 45-41] end is updated to 45 pci_bus 0004:45: busn_res: can not insert [bus 45] under [bus 42-41] (conflicts with (null) [bus 42-41]) pci 0004:42:06.0: devices behind bridge are unusable because [bus 45] cannot be assigned for them pci_bus 0004:46: busn_res: can not insert [bus 46-41] under [bus 42-41] (conflicts with (null) [bus 42-41]) pci_bus 0004:46: busn_res: [bus 46-41] end is updated to 46 pci_bus 0004:46: busn_res: can not insert [bus 46] under [bus 42-41] (conflicts with (null) [bus 42-41]) pci 0004:42:0e.0: devices behind bridge are unusable because [bus 46] cannot be assigned for them pci_bus 0004:42: busn_res: [bus 42-41] end is updated to 46 pci_bus 0004:42: busn_res: can not insert [bus 42-46] under [bus 41] (conflicts with (null) [bus 41]) pci 0004:41:00.0: devices behind bridge are unusable because [bus 42-46] cannot be assigned for them pcieport 0004:40:00.0: bridge has subordinate 41 but max busn 46 During the initial scan, PCI core doesn't see the switch and since the Root Port is not hot plug capable, the secondary bus number gets assigned as the subordinate bus number. This means, the PCI core assumes that only one bus will appear behind the Root Port since the Root Port is not hot plug capable. This works perfectly fine for PCIe endpoints connected to the Root Port, since they don't extend the bus. However, if a PCIe switch is connected, then there is a problem when the downstream busses starts showing up and the PCI core doesn't extend the subordinate bus number after initial scan during boot. The long term plan is to migrate this driver to the pwrctrl framework, once it adds proper support for powering up and enumerating PCIe switches. Cc: stable(a)vger.kernel.org Suggested-by: Manivannan Sadhasivam <mani(a)kernel.org> Acked-by: Shawn Lin <shawn.lin(a)rock-chips.com> Tested-by: Shawn Lin <shawn.lin(a)rock-chips.com> Signed-off-by: Niklas Cassel <cassel(a)kernel.org> --- drivers/pci/controller/dwc/pcie-dw-rockchip.c | 1 - 1 file changed, 1 deletion(-) diff --git a/drivers/pci/controller/dwc/pcie-dw-rockchip.c b/drivers/pci/controller/dwc/pcie-dw-rockchip.c index 8c1c92208802..ca808d8f7975 100644 --- a/drivers/pci/controller/dwc/pcie-dw-rockchip.c +++ b/drivers/pci/controller/dwc/pcie-dw-rockchip.c @@ -601,7 +601,6 @@ static int rockchip_pcie_configure_rc(struct platform_device *pdev, pp = &rockchip->pci.pp; pp->ops = &rockchip_pcie_host_ops; - pp->use_linkup_irq = true; ret = dw_pcie_host_init(pp); if (ret) { -- 2.52.0

1 week

[PATCH v2] net: usb: sr9700: fix incorrect command used to write single register

by Ethan Nelson-Moore

This fixes the device failing to initialize with "error reading MAC address" for me, probably because the incorrect write of NCR_RST to SR_NCR is not actually resetting the device. Fixes: c9b37458e95629b1d1171457afdcc1bf1eb7881d ("USB2NET : SR9700 : One chip USB 1.1 USB2NET SR9700Device Driver Support") Cc: stable(a)vger.kernel.org Signed-off-by: Ethan Nelson-Moore <enelsonmoore(a)gmail.com> --- drivers/net/usb/sr9700.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/drivers/net/usb/sr9700.c b/drivers/net/usb/sr9700.c index 091bc2aca7e8..5d97e95a17b0 100644 --- a/drivers/net/usb/sr9700.c +++ b/drivers/net/usb/sr9700.c @@ -52,7 +52,7 @@ static int sr_read_reg(struct usbnet *dev, u8 reg, u8 *value) static int sr_write_reg(struct usbnet *dev, u8 reg, u8 value) { - return usbnet_write_cmd(dev, SR_WR_REGS, SR_REQ_WR_REG, + return usbnet_write_cmd(dev, SR_WR_REG, SR_REQ_WR_REG, value, reg, NULL, 0); } @@ -65,7 +65,7 @@ static void sr_write_async(struct usbnet *dev, u8 reg, u16 length, static void sr_write_reg_async(struct usbnet *dev, u8 reg, u8 value) { - usbnet_write_cmd_async(dev, SR_WR_REGS, SR_REQ_WR_REG, + usbnet_write_cmd_async(dev, SR_WR_REG, SR_REQ_WR_REG, value, reg, NULL, 0); } -- 2.43.0

1 week

دعوة لنشر الأبحاث والمقالات العلمية

by مجلة طوى للع لوم الاجتما عية

[ View in browser](https://7m8ue.r.ag.d.sendibm3.com/mk/mr/sh/7nVTPdZCTJDXOxg5wYo2dj3… مجلة طُوى للعلوم الاجتماعية =========================== مجلة علمية ، محكمة، فصلية ، مفتوحة الوصول ، تصدر عن مركز فكر للدراسات والتطوير جاء اختيار اسم المجلة “طُوى” استلهامًا من **الوادي المقدّس طُوى**، تعبيرًا عن قدسية المعرفة وأثرها في التغيير المجتمعي، وإيمانًا بأن الفكر العلمي رسالة عميقة لا تقل قداسة عن أي رسالة إنسانية. #### السادة أعضاء الهيئات التدريسية، الباحثون الكرام تحية طيبة وبعد، يسرّ **هيئة تحرير مجلة طُوى للعلوم الاجتماعية** أن تتقدّم إليكم بأطيب التحيات، متمنّين لكم دوام التوفيق والنجاح في مسيرتكم الأكاديمية. نودّ إعلامكم بفتح باب استقبال الأبحاث العلمية للنشر في **العدد الخامس** من المجلة، وذلك ضمن إطار أكاديمي محكّم، وبرسوم رمزية قدرها **50 دولارًا أمريكيًا** فقط. 🔹 **عن المجلة** تُعد مجلة طُوى منصة علمية محكّمة تُعنى بنشر البحوث الأصيلة في مجالات العلوم الاجتماعية ، وقد أسهمت المجلة خلال أعدادها السابقة في نشر عشرات الأبحاث لباحثين من جامعات عربية ودولية، مع الالتزام الصارم بمعايير الجودة والتحكيم العلمي. ✨ **لماذا النشر في مجلة طُوى؟** • تحكيم علمي سريع خلال **7 أيام** • نشر بثلاث لغات: **العربية – الإنجليزية – التركية** • **وصول مفتوح (Open Access)** لجميع القرّاء • ترقيم دولي **ISSN: 3104-7211** • تخصيص **DOI** مستقل لكل مقال • فهرسة في: Google Scholar، ResearchGate، Academia وغيرها في 20 فهرسة • منصة إلكترونية تفاعلية لتقديم ومتابعة المخطوطات 📚 **مجالات النشر** تشمل – ولا تقتصر على: علم الاجتماع، العلوم السياسية، الأنثروبولوجيا، علم النفس الاجتماعي، الإعلام والاتصال، القانون والمجتمع، التربية والتعليم، الاقتصاد الاجتماعي، الجندر وتمكين المرأة، العمل الاجتماعي، الهجرة واللجوء، الدراسات التنموية والبيئية، الفلسفة والتاريخ الاجتماعي. 💲 **رسوم النشر**: 50 دولارًا أمريكيًا، تشمل التحكيم العلمي، التدقيق، والإخراج الفني. 📄 **للتقديم على النشر**: [https://7m8ue.r.ag.d.sendibm3.com/mk/cl/f/sh/7nVU1aA2nfsTSeWOzmWNvJm5IIiZEZ… 🌐 **موقع المجلة**: [https://7m8ue.r.ag.d.sendibm3.com/mk/cl/f/sh/7nVU1aA2nfuMSB1hyLkpxg5tSfDLyV… 📧 **للتواصل عبر البريد الإلكتروني**: [info@tuwa-journal.org](mailto:info@tuwa-journal.org) 📲 **للاستفسار الفوري عبر واتساب**: [https://7m8ue.r.ag.d.sendibm3.com/mk/cl/f/sh/7nVU1aA2nfwFRhX0wuzI02Phd1i8iS… نعتزّ بانضمامكم إلى شبكة باحثي مجلة طُوى، ونتطلّع لاستقبال إسهاماتكم العلمية القيّمة، ومنح أبحاثكم الانتشار الأكاديمي الذي تستحقه. وتفضلوا بقبول فائق الاحترام والتقدير، **هيئة تحرير مجلة طُوى للعلوم الاجتماعية** [ Read the whole story](https://7m8ue.r.ag.d.sendibm3.com/mk/cl/f/sh/7nVU1aA2ng01QkXcu3SC4l3… **fiker for research and development** يمكن متابعة المجلة من خلال الاتصال الموضحة. الموقع: [https://tuwa-journal.org/](https://tuwa-journal.org/) || البريد الإلكتروني: info(a)tuwa-journal.org هاتف: 00905398717003 You've received it because you've subscribed to our newsletter. [Unsubscribe](https://7m8ue.r.ag.d.sendibm3.com/mk/un/v2/sh/7nVTPdbLJ2bPbEmD…

1 week

[PATCH] fbdev: Use device_create_with_groups() to fix sysfs groups registration race

by Hans de Goede

The fbdev sysfs attributes are registered after sending the uevent for the device creation, leaving a race window where e.g. udev rules may not be able to access the sysfs attributes because the registration is not done yet. Fix this by switching to device_create_with_groups(). This also results in a nice cleanup. After switching to device_create_with_groups() all that is left of fb_init_device() is setting the drvdata and that can be passed to device_create[_with_groups]() too. After which fb_init_device() can be completely removed. Dropping fb_init_device() + fb_cleanup_device() in turn allows removing fb_info.class_flag as they were the only user of this field. Fixes: 5fc830d6aca1 ("fbdev: Register sysfs groups through device_add_group") Cc: stable(a)vger.kernel.org Cc: Shixiong Ou <oushixiong(a)kylinos.cn> Signed-off-by: Hans de Goede <johannes.goede(a)oss.qualcomm.com> --- Note the fixes tag is technically wrong. This race has existed forever. The commit I picked for the fixes tag is a dependency of this change not the commit introducing the race. I don't believe that backporting this back any further is useful which is why I went with this commit. --- drivers/video/fbdev/core/fbsysfs.c | 36 +++--------------------------- include/linux/fb.h | 1 - 2 files changed, 3 insertions(+), 34 deletions(-) diff --git a/drivers/video/fbdev/core/fbsysfs.c b/drivers/video/fbdev/core/fbsysfs.c index b8344c40073b..baa2bae0fb5b 100644 --- a/drivers/video/fbdev/core/fbsysfs.c +++ b/drivers/video/fbdev/core/fbsysfs.c @@ -12,8 +12,6 @@ #include "fb_internal.h" -#define FB_SYSFS_FLAG_ATTR 1 - static int activate(struct fb_info *fb_info, struct fb_var_screeninfo *var) { int err; @@ -451,33 +449,7 @@ static struct attribute *fb_device_attrs[] = { NULL, }; -static const struct attribute_group fb_device_attr_group = { - .attrs = fb_device_attrs, -}; - -static int fb_init_device(struct fb_info *fb_info) -{ - int ret; - - dev_set_drvdata(fb_info->dev, fb_info); - - fb_info->class_flag |= FB_SYSFS_FLAG_ATTR; - - ret = device_add_group(fb_info->dev, &fb_device_attr_group); - if (ret) - fb_info->class_flag &= ~FB_SYSFS_FLAG_ATTR; - - return 0; -} - -static void fb_cleanup_device(struct fb_info *fb_info) -{ - if (fb_info->class_flag & FB_SYSFS_FLAG_ATTR) { - device_remove_group(fb_info->dev, &fb_device_attr_group); - - fb_info->class_flag &= ~FB_SYSFS_FLAG_ATTR; - } -} +ATTRIBUTE_GROUPS(fb_device); int fb_device_create(struct fb_info *fb_info) { @@ -485,14 +457,13 @@ int fb_device_create(struct fb_info *fb_info) dev_t devt = MKDEV(FB_MAJOR, node); int ret; - fb_info->dev = device_create(fb_class, fb_info->device, devt, NULL, "fb%d", node); + fb_info->dev = device_create_with_groups(fb_class, fb_info->device, devt, fb_info, + fb_device_groups, "fb%d", node); if (IS_ERR(fb_info->dev)) { /* Not fatal */ ret = PTR_ERR(fb_info->dev); pr_warn("Unable to create device for framebuffer %d; error %d\n", node, ret); fb_info->dev = NULL; - } else { - fb_init_device(fb_info); } return 0; @@ -505,7 +476,6 @@ void fb_device_destroy(struct fb_info *fb_info) if (!fb_info->dev) return; - fb_cleanup_device(fb_info); device_destroy(fb_class, devt); fb_info->dev = NULL; } diff --git a/include/linux/fb.h b/include/linux/fb.h index 05cc251035da..c3302d513546 100644 --- a/include/linux/fb.h +++ b/include/linux/fb.h @@ -497,7 +497,6 @@ struct fb_info { #if defined(CONFIG_FB_DEVICE) struct device *dev; /* This is this fb device */ #endif - int class_flag; /* private sysfs flags */ #ifdef CONFIG_FB_TILEBLITTING struct fb_tile_ops *tileops; /* Tile Blitting */ #endif -- 2.52.0

1 week

[PATCH] eisa/pci_eisa: Fix PCI device refcount leak on early init error

by Kaushlendra Kumar

The for_each_pci_dev() loop takes a reference on each PCI device during iteration. When returning early on pci_eisa_init() failure, the reference on 'dev' is not released, causing a resource leak. Add pci_dev_put(dev) before the error return to properly balance the reference count taken by for_each_pci_dev(). Fixes: c5fb301ae83b ("EISA/PCI: Init EISA early, before PNP") Cc: stable(a)vger.kernel.org Signed-off-by: Kaushlendra Kumar <kaushlendra.kumar(a)intel.com> --- drivers/eisa/pci_eisa.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/drivers/eisa/pci_eisa.c b/drivers/eisa/pci_eisa.c index 8173e60bb808..8242e9e16ce2 100644 --- a/drivers/eisa/pci_eisa.c +++ b/drivers/eisa/pci_eisa.c @@ -80,8 +80,10 @@ static int __init pci_eisa_init_early(void) for_each_pci_dev(dev) if ((dev->class >> 8) == PCI_CLASS_BRIDGE_EISA) { ret = pci_eisa_init(dev); - if (ret) + if (ret) { + pci_dev_put(dev); return ret; + } } return 0; -- 2.34.1

1 week

FAILED: patch "[PATCH] mm/ksm: fix exec/fork inheritance support for prctl" failed to apply to 6.12-stable tree

by gregkh＠linuxfoundation.org

The patch below does not apply to the 6.12-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <stable(a)vger.kernel.org>. To reproduce the conflict and resubmit, you may use the following commands: git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.12.y git checkout FETCH_HEAD git cherry-pick -x 590c03ca6a3fbb114396673314e2aa483839608b # <resolve conflicts, build, test, etc.> git commit -s git send-email --to '<stable(a)vger.kernel.org>' --in-reply-to '2025122924-reproach-foster-4189@gregkh' --subject-prefix 'PATCH 6.12.y' HEAD^.. Possible dependencies: thanks, greg k-h ------------------ original commit in Linus's tree ------------------ From 590c03ca6a3fbb114396673314e2aa483839608b Mon Sep 17 00:00:00 2001 From: xu xin <xu.xin16(a)zte.com.cn> Date: Tue, 7 Oct 2025 18:28:21 +0800 Subject: [PATCH] mm/ksm: fix exec/fork inheritance support for prctl Patch series "ksm: fix exec/fork inheritance", v2. This series fixes exec/fork inheritance. See the detailed description of the issue below. This patch (of 2): Background ========== commit d7597f59d1d33 ("mm: add new api to enable ksm per process") introduced MMF_VM_MERGE_ANY for mm->flags, and allowed user to set it by prctl() so that the process's VMAs are forcibly scanned by ksmd. Subsequently, the 3c6f33b7273a ("mm/ksm: support fork/exec for prctl") supported inheriting the MMF_VM_MERGE_ANY flag when a task calls execve(). Finally, commit 3a9e567ca45fb ("mm/ksm: fix ksm exec support for prctl") fixed the issue that ksmd doesn't scan the mm_struct with MMF_VM_MERGE_ANY by adding the mm_slot to ksm_mm_head in __bprm_mm_init(). Problem ======= In some extreme scenarios, however, this inheritance of MMF_VM_MERGE_ANY during exec/fork can fail. For example, when the scanning frequency of ksmd is tuned extremely high, a process carrying MMF_VM_MERGE_ANY may still fail to pass it to the newly exec'd process. This happens because ksm_execve() is executed too early in the do_execve flow (prematurely adding the new mm_struct to the ksm_mm_slot list). As a result, before do_execve completes, ksmd may have already performed a scan and found that this new mm_struct has no VM_MERGEABLE VMAs, thus clearing its MMF_VM_MERGE_ANY flag. Consequently, when the new program executes, the flag MMF_VM_MERGE_ANY inheritance missed. Root reason =========== commit d7597f59d1d33 ("mm: add new api to enable ksm per process") clear the flag MMF_VM_MERGE_ANY when ksmd found no VM_MERGEABLE VMAs. Solution ======== Firstly, Don't clear MMF_VM_MERGE_ANY when ksmd found no VM_MERGEABLE VMAs, because perhaps their mm_struct has just been added to ksm_mm_slot list, and its process has not yet officially started running or has not yet performed mmap/brk to allocate anonymous VMAS. Secondly, recheck MMF_VM_MERGEABLE again if a process takes MMF_VM_MERGE_ANY, and create a mm_slot and join it into ksm_scan_list again. Link: https://lkml.kernel.org/r/20251007182504440BJgK8VXRHh8TD7IGSUIY4@zte.com.cn Link: https://lkml.kernel.org/r/20251007182821572h_SoFqYZXEP1mvWI4n9VL@zte.com.cn Fixes: 3c6f33b7273a ("mm/ksm: support fork/exec for prctl") Fixes: d7597f59d1d3 ("mm: add new api to enable ksm per process") Signed-off-by: xu xin <xu.xin16(a)zte.com.cn> Cc: Stefan Roesch <shr(a)devkernel.io> Cc: David Hildenbrand <david(a)redhat.com> Cc: Jinjiang Tu <tujinjiang(a)huawei.com> Cc: Wang Yaxin <wang.yaxin(a)zte.com.cn> Cc: Yang Yang <yang.yang29(a)zte.com.cn> Cc: <stable(a)vger.kernel.org> Signed-off-by: Andrew Morton <akpm(a)linux-foundation.org> diff --git a/include/linux/ksm.h b/include/linux/ksm.h index 067538fc4d58..c982694c987b 100644 --- a/include/linux/ksm.h +++ b/include/linux/ksm.h @@ -17,7 +17,7 @@ #ifdef CONFIG_KSM int ksm_madvise(struct vm_area_struct *vma, unsigned long start, unsigned long end, int advice, vm_flags_t *vm_flags); -vm_flags_t ksm_vma_flags(const struct mm_struct *mm, const struct file *file, +vm_flags_t ksm_vma_flags(struct mm_struct *mm, const struct file *file, vm_flags_t vm_flags); int ksm_enable_merge_any(struct mm_struct *mm); int ksm_disable_merge_any(struct mm_struct *mm); @@ -103,7 +103,7 @@ bool ksm_process_mergeable(struct mm_struct *mm); #else /* !CONFIG_KSM */ -static inline vm_flags_t ksm_vma_flags(const struct mm_struct *mm, +static inline vm_flags_t ksm_vma_flags(struct mm_struct *mm, const struct file *file, vm_flags_t vm_flags) { return vm_flags; diff --git a/mm/ksm.c b/mm/ksm.c index cdefba633856..4f672f4f2140 100644 --- a/mm/ksm.c +++ b/mm/ksm.c @@ -2712,8 +2712,14 @@ static struct ksm_rmap_item *scan_get_next_rmap_item(struct page **page) spin_unlock(&ksm_mmlist_lock); mm_slot_free(mm_slot_cache, mm_slot); + /* + * Only clear MMF_VM_MERGEABLE. We must not clear + * MMF_VM_MERGE_ANY, because for those MMF_VM_MERGE_ANY process, + * perhaps their mm_struct has just been added to ksm_mm_slot + * list, and its process has not yet officially started running + * or has not yet performed mmap/brk to allocate anonymous VMAS. + */ mm_flags_clear(MMF_VM_MERGEABLE, mm); - mm_flags_clear(MMF_VM_MERGE_ANY, mm); mmap_read_unlock(mm); mmdrop(mm); } else { @@ -2831,12 +2837,20 @@ static int __ksm_del_vma(struct vm_area_struct *vma) * * Returns: @vm_flags possibly updated to mark mergeable. */ -vm_flags_t ksm_vma_flags(const struct mm_struct *mm, const struct file *file, +vm_flags_t ksm_vma_flags(struct mm_struct *mm, const struct file *file, vm_flags_t vm_flags) { if (mm_flags_test(MMF_VM_MERGE_ANY, mm) && - __ksm_should_add_vma(file, vm_flags)) + __ksm_should_add_vma(file, vm_flags)) { vm_flags |= VM_MERGEABLE; + /* + * Generally, the flags here always include MMF_VM_MERGEABLE. + * However, in rare cases, this flag may be cleared by ksmd who + * scans a cycle without finding any mergeable vma. + */ + if (unlikely(!mm_flags_test(MMF_VM_MERGEABLE, mm))) + __ksm_enter(mm); + } return vm_flags; }

1 week

FAILED: patch "[PATCH] mm/ksm: fix exec/fork inheritance support for prctl" failed to apply to 6.6-stable tree

by gregkh＠linuxfoundation.org

The patch below does not apply to the 6.6-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <stable(a)vger.kernel.org>. To reproduce the conflict and resubmit, you may use the following commands: git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.6.y git checkout FETCH_HEAD git cherry-pick -x 590c03ca6a3fbb114396673314e2aa483839608b # <resolve conflicts, build, test, etc.> git commit -s git send-email --to '<stable(a)vger.kernel.org>' --in-reply-to '2025122925-designed-overture-2e7d@gregkh' --subject-prefix 'PATCH 6.6.y' HEAD^.. Possible dependencies: thanks, greg k-h ------------------ original commit in Linus's tree ------------------ From 590c03ca6a3fbb114396673314e2aa483839608b Mon Sep 17 00:00:00 2001 From: xu xin <xu.xin16(a)zte.com.cn> Date: Tue, 7 Oct 2025 18:28:21 +0800 Subject: [PATCH] mm/ksm: fix exec/fork inheritance support for prctl Patch series "ksm: fix exec/fork inheritance", v2. This series fixes exec/fork inheritance. See the detailed description of the issue below. This patch (of 2): Background ========== commit d7597f59d1d33 ("mm: add new api to enable ksm per process") introduced MMF_VM_MERGE_ANY for mm->flags, and allowed user to set it by prctl() so that the process's VMAs are forcibly scanned by ksmd. Subsequently, the 3c6f33b7273a ("mm/ksm: support fork/exec for prctl") supported inheriting the MMF_VM_MERGE_ANY flag when a task calls execve(). Finally, commit 3a9e567ca45fb ("mm/ksm: fix ksm exec support for prctl") fixed the issue that ksmd doesn't scan the mm_struct with MMF_VM_MERGE_ANY by adding the mm_slot to ksm_mm_head in __bprm_mm_init(). Problem ======= In some extreme scenarios, however, this inheritance of MMF_VM_MERGE_ANY during exec/fork can fail. For example, when the scanning frequency of ksmd is tuned extremely high, a process carrying MMF_VM_MERGE_ANY may still fail to pass it to the newly exec'd process. This happens because ksm_execve() is executed too early in the do_execve flow (prematurely adding the new mm_struct to the ksm_mm_slot list). As a result, before do_execve completes, ksmd may have already performed a scan and found that this new mm_struct has no VM_MERGEABLE VMAs, thus clearing its MMF_VM_MERGE_ANY flag. Consequently, when the new program executes, the flag MMF_VM_MERGE_ANY inheritance missed. Root reason =========== commit d7597f59d1d33 ("mm: add new api to enable ksm per process") clear the flag MMF_VM_MERGE_ANY when ksmd found no VM_MERGEABLE VMAs. Solution ======== Firstly, Don't clear MMF_VM_MERGE_ANY when ksmd found no VM_MERGEABLE VMAs, because perhaps their mm_struct has just been added to ksm_mm_slot list, and its process has not yet officially started running or has not yet performed mmap/brk to allocate anonymous VMAS. Secondly, recheck MMF_VM_MERGEABLE again if a process takes MMF_VM_MERGE_ANY, and create a mm_slot and join it into ksm_scan_list again. Link: https://lkml.kernel.org/r/20251007182504440BJgK8VXRHh8TD7IGSUIY4@zte.com.cn Link: https://lkml.kernel.org/r/20251007182821572h_SoFqYZXEP1mvWI4n9VL@zte.com.cn Fixes: 3c6f33b7273a ("mm/ksm: support fork/exec for prctl") Fixes: d7597f59d1d3 ("mm: add new api to enable ksm per process") Signed-off-by: xu xin <xu.xin16(a)zte.com.cn> Cc: Stefan Roesch <shr(a)devkernel.io> Cc: David Hildenbrand <david(a)redhat.com> Cc: Jinjiang Tu <tujinjiang(a)huawei.com> Cc: Wang Yaxin <wang.yaxin(a)zte.com.cn> Cc: Yang Yang <yang.yang29(a)zte.com.cn> Cc: <stable(a)vger.kernel.org> Signed-off-by: Andrew Morton <akpm(a)linux-foundation.org> diff --git a/include/linux/ksm.h b/include/linux/ksm.h index 067538fc4d58..c982694c987b 100644 --- a/include/linux/ksm.h +++ b/include/linux/ksm.h @@ -17,7 +17,7 @@ #ifdef CONFIG_KSM int ksm_madvise(struct vm_area_struct *vma, unsigned long start, unsigned long end, int advice, vm_flags_t *vm_flags); -vm_flags_t ksm_vma_flags(const struct mm_struct *mm, const struct file *file, +vm_flags_t ksm_vma_flags(struct mm_struct *mm, const struct file *file, vm_flags_t vm_flags); int ksm_enable_merge_any(struct mm_struct *mm); int ksm_disable_merge_any(struct mm_struct *mm); @@ -103,7 +103,7 @@ bool ksm_process_mergeable(struct mm_struct *mm); #else /* !CONFIG_KSM */ -static inline vm_flags_t ksm_vma_flags(const struct mm_struct *mm, +static inline vm_flags_t ksm_vma_flags(struct mm_struct *mm, const struct file *file, vm_flags_t vm_flags) { return vm_flags; diff --git a/mm/ksm.c b/mm/ksm.c index cdefba633856..4f672f4f2140 100644 --- a/mm/ksm.c +++ b/mm/ksm.c @@ -2712,8 +2712,14 @@ static struct ksm_rmap_item *scan_get_next_rmap_item(struct page **page) spin_unlock(&ksm_mmlist_lock); mm_slot_free(mm_slot_cache, mm_slot); + /* + * Only clear MMF_VM_MERGEABLE. We must not clear + * MMF_VM_MERGE_ANY, because for those MMF_VM_MERGE_ANY process, + * perhaps their mm_struct has just been added to ksm_mm_slot + * list, and its process has not yet officially started running + * or has not yet performed mmap/brk to allocate anonymous VMAS. + */ mm_flags_clear(MMF_VM_MERGEABLE, mm); - mm_flags_clear(MMF_VM_MERGE_ANY, mm); mmap_read_unlock(mm); mmdrop(mm); } else { @@ -2831,12 +2837,20 @@ static int __ksm_del_vma(struct vm_area_struct *vma) * * Returns: @vm_flags possibly updated to mark mergeable. */ -vm_flags_t ksm_vma_flags(const struct mm_struct *mm, const struct file *file, +vm_flags_t ksm_vma_flags(struct mm_struct *mm, const struct file *file, vm_flags_t vm_flags) { if (mm_flags_test(MMF_VM_MERGE_ANY, mm) && - __ksm_should_add_vma(file, vm_flags)) + __ksm_should_add_vma(file, vm_flags)) { vm_flags |= VM_MERGEABLE; + /* + * Generally, the flags here always include MMF_VM_MERGEABLE. + * However, in rare cases, this flag may be cleared by ksmd who + * scans a cycle without finding any mergeable vma. + */ + if (unlikely(!mm_flags_test(MMF_VM_MERGEABLE, mm))) + __ksm_enter(mm); + } return vm_flags; }

1 week

[PATCH 5.15.y RESEND] KVM: arm64: sys_regs: disable -Wuninitialized-const-pointer warning

by Justin Stitt

A new warning in Clang 22 [1] complains that @clidr passed to get_clidr_el1() is an uninitialized const pointer. get_clidr_el1() doesn't really care since it casts away the const-ness anyways -- it is a false positive. | ../arch/arm64/kvm/sys_regs.c:2838:23: warning: variable 'clidr' is uninitialized when passed as a const pointer argument here [-Wuninitialized-const-pointer] | 2838 | get_clidr_el1(NULL, &clidr); /* Ugly... */ | | ^~~~~ This patch isn't needed for anything past 6.1 as this code section was reworked in Commit 7af0c2534f4c ("KVM: arm64: Normalize cache configuration"). Since there is no upstream equivalent, this patch just needs to be applied to 5.15. Disable this warning for sys_regs.o with an iron fist as it doesn't make sense to waste maintainer's time or potentially break builds by backporting large changelists from 6.2+. Cc: stable(a)vger.kernel.org Fixes: 7c8c5e6a9101e ("arm64: KVM: system register handling") Link: https://github.com/llvm/llvm-project/commit/00dacf8c22f065cb52efb14cd091d44… [1] Reviewed-by: Nathan Chancellor <nathan(a)kernel.org> Signed-off-by: Justin Stitt <justinstitt(a)google.com> --- Resending this with Nathan's RB tag, an updated commit log and better recipients from checkpatch.pl. I'm also sending a similar patch resend for 6.1. --- arch/arm64/kvm/Makefile | 3 +++ 1 file changed, 3 insertions(+) diff --git a/arch/arm64/kvm/Makefile b/arch/arm64/kvm/Makefile index 989bb5dad2c8..109cca425d3e 100644 --- a/arch/arm64/kvm/Makefile +++ b/arch/arm64/kvm/Makefile @@ -25,3 +25,6 @@ kvm-y := $(KVM)/kvm_main.o $(KVM)/coalesced_mmio.o $(KVM)/eventfd.o \ vgic/vgic-its.o vgic/vgic-debug.o kvm-$(CONFIG_HW_PERF_EVENTS) += pmu-emul.o + +# Work around a false positive Clang 22 -Wuninitialized-const-pointer warning +CFLAGS_sys_regs.o := $(call cc-disable-warning, uninitialized-const-pointer) --- base-commit: 8bb7eca972ad531c9b149c0a51ab43a417385813 change-id: 20250728-b4-stable-disable-uninit-ptr-warn-5-15-c0c9db3df206 Best regards, -- Justin Stitt <justinstitt(a)google.com>

1 week

[PATCH 6.1.y RESEND v2] KVM: arm64: sys_regs: disable -Wuninitialized-const-pointer warning

by Justin Stitt

A new warning in Clang 22 [1] complains that @clidr passed to get_clidr_el1() is an uninitialized const pointer. get_clidr_el1() doesn't really care since it casts away the const-ness anyways -- it is a false positive. This patch isn't needed for anything past 6.1 as this code section was reworked in Commit 7af0c2534f4c ("KVM: arm64: Normalize cache configuration") which incidentally removed the aforementioned warning. Since there is no upstream equivalent, this patch just needs to be applied to 6.1. Disable this warning for sys_regs.o instead of backporting the patches from 6.2+ that modified this code area. Cc: stable(a)vger.kernel.org Fixes: 7c8c5e6a9101e ("arm64: KVM: system register handling") Link: https://github.com/llvm/llvm-project/commit/00dacf8c22f065cb52efb14cd091d44… [1] Reviewed-by: Nathan Chancellor <nathan(a)kernel.org> Signed-off-by: Justin Stitt <justinstitt(a)google.com> --- Changes in v2: - disable warning for TU instead of initialising the struct - update commit message - Link to v1: https://lore.kernel.org/all/20250724-b4-clidr-unint-const-ptr-v1-1-67c4d620… - Link to v1 resend (sent wrong diff, thanks Nathan): https://lore.kernel.org/all/20251204-b4-clidr-unint-const-ptr-v1-1-95161315… --- arch/arm64/kvm/Makefile | 3 +++ 1 file changed, 3 insertions(+) diff --git a/arch/arm64/kvm/Makefile b/arch/arm64/kvm/Makefile index 5e33c2d4645a..5fdb5331bfad 100644 --- a/arch/arm64/kvm/Makefile +++ b/arch/arm64/kvm/Makefile @@ -24,6 +24,9 @@ kvm-y += arm.o mmu.o mmio.o psci.o hypercalls.o pvtime.o \ kvm-$(CONFIG_HW_PERF_EVENTS) += pmu-emul.o pmu.o +# Work around a false positive Clang 22 -Wuninitialized-const-pointer warning +CFLAGS_sys_regs.o := $(call cc-disable-warning, uninitialized-const-pointer) + always-y := hyp_constants.h hyp-constants.s define rule_gen_hyp_constants --- base-commit: 830b3c68c1fb1e9176028d02ef86f3cf76aa2476 change-id: 20250728-stable-disable-unit-ptr-warn-281fee82539c Best regards, -- Justin Stitt <justinstitt(a)google.com>

1 week

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