January 2025 - Linux-stable-mirror

[PATCH] replace free hugepage folios after migration

by yangge1116＠126.com

From: yangge <yangge1116(a)126.com> My machine has 4 NUMA nodes, each equipped with 32GB of memory. I have configured each NUMA node with 16GB of CMA and 16GB of in-use hugetlb pages. The allocation of contiguous memory via the cma_alloc() function can fail probabilistically. The cma_alloc() function may fail if it sees an in-use hugetlb page within the allocation range, even if that page has already been migrated. When in-use hugetlb pages are migrated, they may simply be released back into the free hugepage pool instead of being returned to the buddy system. This can cause the test_pages_isolated() function check to fail, ultimately leading to the failure of the cma_alloc() function: cma_alloc() __alloc_contig_migrate_range() // migrate in-use hugepage test_pages_isolated() __test_page_isolated_in_pageblock() PageBuddy(page) // check if the page is in buddy To address this issue, we will add a function named replace_free_hugepage_folios(). This function will replace the hugepage in the free hugepage pool with a new one and release the old one to the buddy system. After the migration of in-use hugetlb pages is completed, we will invoke the replace_free_hugepage_folios() function to ensure that these hugepages are properly released to the buddy system. Following this step, when the test_pages_isolated() function is executed for inspection, it will successfully pass. Signed-off-by: yangge <yangge1116(a)126.com> --- include/linux/hugetlb.h | 6 ++++++ mm/hugetlb.c | 37 +++++++++++++++++++++++++++++++++++++ mm/page_alloc.c | 13 ++++++++++++- 3 files changed, 55 insertions(+), 1 deletion(-) diff --git a/include/linux/hugetlb.h b/include/linux/hugetlb.h index ae4fe86..7d36ac8 100644 --- a/include/linux/hugetlb.h +++ b/include/linux/hugetlb.h @@ -681,6 +681,7 @@ struct huge_bootmem_page { }; int isolate_or_dissolve_huge_page(struct page *page, struct list_head *list); +int replace_free_hugepage_folios(unsigned long start_pfn, unsigned long end_pfn); struct folio *alloc_hugetlb_folio(struct vm_area_struct *vma, unsigned long addr, int avoid_reserve); struct folio *alloc_hugetlb_folio_nodemask(struct hstate *h, int preferred_nid, @@ -1059,6 +1060,11 @@ static inline int isolate_or_dissolve_huge_page(struct page *page, return -ENOMEM; } +int replace_free_hugepage_folios(unsigned long start_pfn, unsigned long end_pfn) +{ + return 0; +} + static inline struct folio *alloc_hugetlb_folio(struct vm_area_struct *vma, unsigned long addr, int avoid_reserve) diff --git a/mm/hugetlb.c b/mm/hugetlb.c index 8e1db80..a099c54 100644 --- a/mm/hugetlb.c +++ b/mm/hugetlb.c @@ -2975,6 +2975,43 @@ int isolate_or_dissolve_huge_page(struct page *page, struct list_head *list) return ret; } +/* + * replace_free_hugepage_folios - Replace free hugepage folios in a given pfn + * range with new folios. + * @stat_pfn: start pfn of the given pfn range + * @end_pfn: end pfn of the given pfn range + * Returns 0 on success, otherwise negated error. + */ +int replace_free_hugepage_folios(unsigned long start_pfn, unsigned long end_pfn) +{ + struct hstate *h; + struct folio *folio; + int ret = 0; + + LIST_HEAD(isolate_list); + + while (start_pfn < end_pfn) { + folio = pfn_folio(start_pfn); + if (folio_test_hugetlb(folio)) { + h = folio_hstate(folio); + } else { + start_pfn++; + continue; + } + + if (!folio_ref_count(folio)) { + ret = alloc_and_dissolve_hugetlb_folio(h, folio, &isolate_list); + if (ret) + break; + + putback_movable_pages(&isolate_list); + } + start_pfn++; + } + + return ret; +} + struct folio *alloc_hugetlb_folio(struct vm_area_struct *vma, unsigned long addr, int avoid_reserve) { diff --git a/mm/page_alloc.c b/mm/page_alloc.c index dde19db..1dcea28 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -6504,7 +6504,18 @@ int alloc_contig_range_noprof(unsigned long start, unsigned long end, ret = __alloc_contig_migrate_range(&cc, start, end, migratetype); if (ret && ret != -EBUSY) goto done; - ret = 0; + + /* + * When in-use hugetlb pages are migrated, they may simply be + * released back into the free hugepage pool instead of being + * returned to the buddy system. After the migration of in-use + * huge pages is completed, we will invoke the + * replace_free_hugepage_folios() function to ensure that + * these hugepages are properly released to the buddy system. + */ + ret = replace_free_hugepage_folios(start, end); + if (ret) + goto done; /* * Pages from [start, end) are within a pageblock_nr_pages -- 2.7.4

8 months

5
13
0 0

[PATCH v4 resend] drm/meson: switch to a managed drm device

by Anastasia Belova

Switch to a managed drm device to cleanup some error handling and make future work easier. Fix dereference of NULL in meson_drv_bind_master by removing drm_dev_put(drm) before meson_encoder_*_remove and component_unbind_all where drm is dereferenced. Co-developed by Linux Verification Center (linuxtesting.org). Cc: stable(a)vger.kernel.org Fixes: 6a044642988b ("drm/meson: fix unbind path if HDMI fails to bind") Signed-off-by: Anastasia Belova <abelova(a)astralinux.ru> --- v2: fix commit message and add Cc: stable(a)vger.kernel.org v3: cleanup error paths v4: fix build errors drivers/gpu/drm/meson/meson_crtc.c | 10 +-- drivers/gpu/drm/meson/meson_drv.c | 93 ++++++++++------------ drivers/gpu/drm/meson/meson_drv.h | 3 +- drivers/gpu/drm/meson/meson_encoder_cvbs.c | 8 +- drivers/gpu/drm/meson/meson_encoder_dsi.c | 2 +- drivers/gpu/drm/meson/meson_encoder_hdmi.c | 4 +- drivers/gpu/drm/meson/meson_overlay.c | 8 +- drivers/gpu/drm/meson/meson_plane.c | 10 +-- 8 files changed, 63 insertions(+), 75 deletions(-) diff --git a/drivers/gpu/drm/meson/meson_crtc.c b/drivers/gpu/drm/meson/meson_crtc.c index d70616da8ce2..e1c0bf3baeea 100644 --- a/drivers/gpu/drm/meson/meson_crtc.c +++ b/drivers/gpu/drm/meson/meson_crtc.c @@ -662,13 +662,13 @@ void meson_crtc_irq(struct meson_drm *priv) drm_crtc_handle_vblank(priv->crtc); - spin_lock_irqsave(&priv->drm->event_lock, flags); + spin_lock_irqsave(&priv->drm.event_lock, flags); if (meson_crtc->event) { drm_crtc_send_vblank_event(priv->crtc, meson_crtc->event); drm_crtc_vblank_put(priv->crtc); meson_crtc->event = NULL; } - spin_unlock_irqrestore(&priv->drm->event_lock, flags); + spin_unlock_irqrestore(&priv->drm.event_lock, flags); } int meson_crtc_create(struct meson_drm *priv) @@ -677,18 +677,18 @@ int meson_crtc_create(struct meson_drm *priv) struct drm_crtc *crtc; int ret; - meson_crtc = devm_kzalloc(priv->drm->dev, sizeof(*meson_crtc), + meson_crtc = devm_kzalloc(priv->drm.dev, sizeof(*meson_crtc), GFP_KERNEL); if (!meson_crtc) return -ENOMEM; meson_crtc->priv = priv; crtc = &meson_crtc->base; - ret = drm_crtc_init_with_planes(priv->drm, crtc, + ret = drm_crtc_init_with_planes(&priv->drm, crtc, priv->primary_plane, NULL, &meson_crtc_funcs, "meson_crtc"); if (ret) { - dev_err(priv->drm->dev, "Failed to init CRTC\n"); + dev_err(priv->drm.dev, "Failed to init CRTC\n"); return ret; } diff --git a/drivers/gpu/drm/meson/meson_drv.c b/drivers/gpu/drm/meson/meson_drv.c index 4bd0baa2a4f5..dd87c6b61e9e 100644 --- a/drivers/gpu/drm/meson/meson_drv.c +++ b/drivers/gpu/drm/meson/meson_drv.c @@ -182,7 +182,6 @@ static int meson_drv_bind_master(struct device *dev, bool has_components) struct platform_device *pdev = to_platform_device(dev); const struct meson_drm_match_data *match; struct meson_drm *priv; - struct drm_device *drm; struct resource *res; void __iomem *regs; int ret, i; @@ -197,58 +196,49 @@ static int meson_drv_bind_master(struct device *dev, bool has_components) if (!match) return -ENODEV; - drm = drm_dev_alloc(&meson_driver, dev); - if (IS_ERR(drm)) - return PTR_ERR(drm); + priv = devm_drm_dev_alloc(dev, &meson_driver, + struct meson_drm, drm); - priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL); - if (!priv) { - ret = -ENOMEM; - goto free_drm; - } - drm->dev_private = priv; - priv->drm = drm; + if (IS_ERR(priv)) + return PTR_ERR(priv); + + priv->drm.dev_private = priv; priv->dev = dev; priv->compat = match->compat; priv->afbcd.ops = match->afbcd_ops; regs = devm_platform_ioremap_resource_byname(pdev, "vpu"); if (IS_ERR(regs)) { - ret = PTR_ERR(regs); - goto free_drm; + return PTR_ERR(regs); } priv->io_base = regs; res = platform_get_resource_byname(pdev, IORESOURCE_MEM, "hhi"); if (!res) { - ret = -EINVAL; - goto free_drm; + return -EINVAL; } /* Simply ioremap since it may be a shared register zone */ regs = devm_ioremap(dev, res->start, resource_size(res)); if (!regs) { - ret = -EADDRNOTAVAIL; - goto free_drm; + return -EADDRNOTAVAIL; } priv->hhi = devm_regmap_init_mmio(dev, regs, &meson_regmap_config); if (IS_ERR(priv->hhi)) { dev_err(&pdev->dev, "Couldn't create the HHI regmap\n"); - ret = PTR_ERR(priv->hhi); - goto free_drm; + return PTR_ERR(priv->hhi); } priv->canvas = meson_canvas_get(dev); if (IS_ERR(priv->canvas)) { - ret = PTR_ERR(priv->canvas); - goto free_drm; + return PTR_ERR(priv->canvas); } ret = meson_canvas_alloc(priv->canvas, &priv->canvas_id_osd1); if (ret) - goto free_drm; + return ret; ret = meson_canvas_alloc(priv->canvas, &priv->canvas_id_vd1_0); if (ret) goto free_canvas_osd1; @@ -261,7 +251,7 @@ static int meson_drv_bind_master(struct device *dev, bool has_components) priv->vsync_irq = platform_get_irq(pdev, 0); - ret = drm_vblank_init(drm, 1); + ret = drm_vblank_init(&priv->drm, 1); if (ret) goto free_canvas_vd1_2; @@ -281,13 +271,13 @@ static int meson_drv_bind_master(struct device *dev, bool has_components) if (ret) goto free_canvas_vd1_2; - ret = drmm_mode_config_init(drm); + ret = drmm_mode_config_init(&priv->drm); if (ret) goto free_canvas_vd1_2; - drm->mode_config.max_width = 3840; - drm->mode_config.max_height = 2160; - drm->mode_config.funcs = &meson_mode_config_funcs; - drm->mode_config.helper_private = &meson_mode_config_helpers; + priv->drm.mode_config.max_width = 3840; + priv->drm.mode_config.max_height = 2160; + priv->drm.mode_config.funcs = &meson_mode_config_funcs; + priv->drm.mode_config.helper_private = &meson_mode_config_helpers; /* Hardware Initialization */ @@ -308,9 +298,9 @@ static int meson_drv_bind_master(struct device *dev, bool has_components) goto exit_afbcd; if (has_components) { - ret = component_bind_all(dev, drm); + ret = component_bind_all(dev, &priv->drm); if (ret) { - dev_err(drm->dev, "Couldn't bind all components\n"); + dev_err(priv->drm.dev, "Couldn't bind all components\n"); /* Do not try to unbind */ has_components = false; goto exit_afbcd; @@ -319,46 +309,49 @@ static int meson_drv_bind_master(struct device *dev, bool has_components) ret = meson_encoder_hdmi_probe(priv); if (ret) - goto exit_afbcd; + goto unbind_components; if (meson_vpu_is_compatible(priv, VPU_COMPATIBLE_G12A)) { ret = meson_encoder_dsi_probe(priv); if (ret) - goto exit_afbcd; + goto unbind_components; } ret = meson_plane_create(priv); if (ret) - goto exit_afbcd; + goto unbind_components; ret = meson_overlay_create(priv); if (ret) - goto exit_afbcd; + goto unbind_components; ret = meson_crtc_create(priv); if (ret) - goto exit_afbcd; + goto unbind_components; - ret = request_irq(priv->vsync_irq, meson_irq, 0, drm->driver->name, drm); + ret = request_irq(priv->vsync_irq, meson_irq, 0, priv->drm.driver->name, &priv->drm); if (ret) - goto exit_afbcd; + goto unbind_components; - drm_mode_config_reset(drm); + drm_mode_config_reset(&priv->drm); - drm_kms_helper_poll_init(drm); + drm_kms_helper_poll_init(&priv->drm); platform_set_drvdata(pdev, priv); - ret = drm_dev_register(drm, 0); + ret = drm_dev_register(&priv->drm, 0); if (ret) goto uninstall_irq; - drm_fbdev_dma_setup(drm, 32); + drm_fbdev_dma_setup(&priv->drm, 32); return 0; uninstall_irq: - free_irq(priv->vsync_irq, drm); + free_irq(priv->vsync_irq, &priv->drm); +unbind_components: + if (has_components) + component_unbind_all(dev, &priv->drm); exit_afbcd: if (priv->afbcd.ops) priv->afbcd.ops->exit(priv); @@ -370,16 +363,11 @@ static int meson_drv_bind_master(struct device *dev, bool has_components) meson_canvas_free(priv->canvas, priv->canvas_id_vd1_0); free_canvas_osd1: meson_canvas_free(priv->canvas, priv->canvas_id_osd1); -free_drm: - drm_dev_put(drm); meson_encoder_dsi_remove(priv); meson_encoder_hdmi_remove(priv); meson_encoder_cvbs_remove(priv); - if (has_components) - component_unbind_all(dev, drm); - return ret; } @@ -391,7 +379,7 @@ static int meson_drv_bind(struct device *dev) static void meson_drv_unbind(struct device *dev) { struct meson_drm *priv = dev_get_drvdata(dev); - struct drm_device *drm = priv->drm; + struct drm_device *drm = &priv->drm; if (priv->canvas) { meson_canvas_free(priv->canvas, priv->canvas_id_osd1); @@ -404,7 +392,6 @@ static void meson_drv_unbind(struct device *dev) drm_kms_helper_poll_fini(drm); drm_atomic_helper_shutdown(drm); free_irq(priv->vsync_irq, drm); - drm_dev_put(drm); meson_encoder_dsi_remove(priv); meson_encoder_hdmi_remove(priv); @@ -428,7 +415,7 @@ static int __maybe_unused meson_drv_pm_suspend(struct device *dev) if (!priv) return 0; - return drm_mode_config_helper_suspend(priv->drm); + return drm_mode_config_helper_suspend(&priv->drm); } static int __maybe_unused meson_drv_pm_resume(struct device *dev) @@ -445,7 +432,7 @@ static int __maybe_unused meson_drv_pm_resume(struct device *dev) if (priv->afbcd.ops) priv->afbcd.ops->init(priv); - return drm_mode_config_helper_resume(priv->drm); + return drm_mode_config_helper_resume(&priv->drm); } static void meson_drv_shutdown(struct platform_device *pdev) @@ -455,8 +442,8 @@ static void meson_drv_shutdown(struct platform_device *pdev) if (!priv) return; - drm_kms_helper_poll_fini(priv->drm); - drm_atomic_helper_shutdown(priv->drm); + drm_kms_helper_poll_fini(&priv->drm); + drm_atomic_helper_shutdown(&priv->drm); } /* diff --git a/drivers/gpu/drm/meson/meson_drv.h b/drivers/gpu/drm/meson/meson_drv.h index 3f9345c14f31..45554c701322 100644 --- a/drivers/gpu/drm/meson/meson_drv.h +++ b/drivers/gpu/drm/meson/meson_drv.h @@ -8,6 +8,7 @@ #define __MESON_DRV_H #include <linux/device.h> +#include <drm/drm_device.h> #include <linux/of.h> #include <linux/regmap.h> @@ -53,7 +54,7 @@ struct meson_drm { u8 canvas_id_vd1_1; u8 canvas_id_vd1_2; - struct drm_device *drm; + struct drm_device drm; struct drm_crtc *crtc; struct drm_plane *primary_plane; struct drm_plane *overlay_plane; diff --git a/drivers/gpu/drm/meson/meson_encoder_cvbs.c b/drivers/gpu/drm/meson/meson_encoder_cvbs.c index d1191de855d9..ddca22c8c1ff 100644 --- a/drivers/gpu/drm/meson/meson_encoder_cvbs.c +++ b/drivers/gpu/drm/meson/meson_encoder_cvbs.c @@ -104,7 +104,7 @@ static int meson_encoder_cvbs_get_modes(struct drm_bridge *bridge, for (i = 0; i < MESON_CVBS_MODES_COUNT; ++i) { struct meson_cvbs_mode *meson_mode = &meson_cvbs_modes[i]; - mode = drm_mode_duplicate(priv->drm, &meson_mode->mode); + mode = drm_mode_duplicate(&priv->drm, &meson_mode->mode); if (!mode) { dev_err(priv->dev, "Failed to create a new display mode\n"); return 0; @@ -221,7 +221,7 @@ static const struct drm_bridge_funcs meson_encoder_cvbs_bridge_funcs = { int meson_encoder_cvbs_probe(struct meson_drm *priv) { - struct drm_device *drm = priv->drm; + struct drm_device *drm = &priv->drm; struct meson_encoder_cvbs *meson_encoder_cvbs; struct drm_connector *connector; struct device_node *remote; @@ -256,7 +256,7 @@ int meson_encoder_cvbs_probe(struct meson_drm *priv) meson_encoder_cvbs->priv = priv; /* Encoder */ - ret = drm_simple_encoder_init(priv->drm, &meson_encoder_cvbs->encoder, + ret = drm_simple_encoder_init(&priv->drm, &meson_encoder_cvbs->encoder, DRM_MODE_ENCODER_TVDAC); if (ret) return dev_err_probe(priv->dev, ret, @@ -273,7 +273,7 @@ int meson_encoder_cvbs_probe(struct meson_drm *priv) } /* Initialize & attach Bridge Connector */ - connector = drm_bridge_connector_init(priv->drm, &meson_encoder_cvbs->encoder); + connector = drm_bridge_connector_init(&priv->drm, &meson_encoder_cvbs->encoder); if (IS_ERR(connector)) return dev_err_probe(priv->dev, PTR_ERR(connector), "Unable to create CVBS bridge connector\n"); diff --git a/drivers/gpu/drm/meson/meson_encoder_dsi.c b/drivers/gpu/drm/meson/meson_encoder_dsi.c index 7816902f5907..03bb12c69863 100644 --- a/drivers/gpu/drm/meson/meson_encoder_dsi.c +++ b/drivers/gpu/drm/meson/meson_encoder_dsi.c @@ -132,7 +132,7 @@ int meson_encoder_dsi_probe(struct meson_drm *priv) meson_encoder_dsi->priv = priv; /* Encoder */ - ret = drm_simple_encoder_init(priv->drm, &meson_encoder_dsi->encoder, + ret = drm_simple_encoder_init(&priv->drm, &meson_encoder_dsi->encoder, DRM_MODE_ENCODER_DSI); if (ret) return dev_err_probe(priv->dev, ret, diff --git a/drivers/gpu/drm/meson/meson_encoder_hdmi.c b/drivers/gpu/drm/meson/meson_encoder_hdmi.c index 0593a1cde906..4465d987f85b 100644 --- a/drivers/gpu/drm/meson/meson_encoder_hdmi.c +++ b/drivers/gpu/drm/meson/meson_encoder_hdmi.c @@ -402,7 +402,7 @@ int meson_encoder_hdmi_probe(struct meson_drm *priv) meson_encoder_hdmi->priv = priv; /* Encoder */ - ret = drm_simple_encoder_init(priv->drm, &meson_encoder_hdmi->encoder, + ret = drm_simple_encoder_init(&priv->drm, &meson_encoder_hdmi->encoder, DRM_MODE_ENCODER_TMDS); if (ret) { dev_err_probe(priv->dev, ret, "Failed to init HDMI encoder\n"); @@ -420,7 +420,7 @@ int meson_encoder_hdmi_probe(struct meson_drm *priv) } /* Initialize & attach Bridge Connector */ - meson_encoder_hdmi->connector = drm_bridge_connector_init(priv->drm, + meson_encoder_hdmi->connector = drm_bridge_connector_init(&priv->drm, &meson_encoder_hdmi->encoder); if (IS_ERR(meson_encoder_hdmi->connector)) { ret = dev_err_probe(priv->dev, diff --git a/drivers/gpu/drm/meson/meson_overlay.c b/drivers/gpu/drm/meson/meson_overlay.c index 7f98de38842b..60ee7f758723 100644 --- a/drivers/gpu/drm/meson/meson_overlay.c +++ b/drivers/gpu/drm/meson/meson_overlay.c @@ -484,7 +484,7 @@ static void meson_overlay_atomic_update(struct drm_plane *plane, interlace_mode = new_state->crtc->mode.flags & DRM_MODE_FLAG_INTERLACE; - spin_lock_irqsave(&priv->drm->event_lock, flags); + spin_lock_irqsave(&priv->drm.event_lock, flags); if ((fb->modifier & DRM_FORMAT_MOD_AMLOGIC_FBC(0, 0)) == DRM_FORMAT_MOD_AMLOGIC_FBC(0, 0)) { @@ -717,7 +717,7 @@ static void meson_overlay_atomic_update(struct drm_plane *plane, priv->viu.vd1_enabled = true; - spin_unlock_irqrestore(&priv->drm->event_lock, flags); + spin_unlock_irqrestore(&priv->drm.event_lock, flags); DRM_DEBUG_DRIVER("\n"); } @@ -838,7 +838,7 @@ int meson_overlay_create(struct meson_drm *priv) DRM_DEBUG_DRIVER("\n"); - meson_overlay = devm_kzalloc(priv->drm->dev, sizeof(*meson_overlay), + meson_overlay = devm_kzalloc(priv->drm.dev, sizeof(*meson_overlay), GFP_KERNEL); if (!meson_overlay) return -ENOMEM; @@ -846,7 +846,7 @@ int meson_overlay_create(struct meson_drm *priv) meson_overlay->priv = priv; plane = &meson_overlay->base; - drm_universal_plane_init(priv->drm, plane, 0xFF, + drm_universal_plane_init(&priv->drm, plane, 0xFF, &meson_overlay_funcs, supported_drm_formats, ARRAY_SIZE(supported_drm_formats), diff --git a/drivers/gpu/drm/meson/meson_plane.c b/drivers/gpu/drm/meson/meson_plane.c index b43ac61201f3..13be94309bf4 100644 --- a/drivers/gpu/drm/meson/meson_plane.c +++ b/drivers/gpu/drm/meson/meson_plane.c @@ -157,7 +157,7 @@ static void meson_plane_atomic_update(struct drm_plane *plane, * Update Buffer * Enable Plane */ - spin_lock_irqsave(&priv->drm->event_lock, flags); + spin_lock_irqsave(&priv->drm.event_lock, flags); /* Check if AFBC decoder is required for this buffer */ if ((meson_vpu_is_compatible(priv, VPU_COMPATIBLE_GXM) || @@ -393,7 +393,7 @@ static void meson_plane_atomic_update(struct drm_plane *plane, priv->viu.osd1_enabled = true; - spin_unlock_irqrestore(&priv->drm->event_lock, flags); + spin_unlock_irqrestore(&priv->drm.event_lock, flags); } static void meson_plane_atomic_disable(struct drm_plane *plane, @@ -536,7 +536,7 @@ int meson_plane_create(struct meson_drm *priv) const uint64_t *format_modifiers = format_modifiers_default; int ret; - meson_plane = devm_kzalloc(priv->drm->dev, sizeof(*meson_plane), + meson_plane = devm_kzalloc(priv->drm.dev, sizeof(*meson_plane), GFP_KERNEL); if (!meson_plane) return -ENOMEM; @@ -549,14 +549,14 @@ int meson_plane_create(struct meson_drm *priv) else if (meson_vpu_is_compatible(priv, VPU_COMPATIBLE_G12A)) format_modifiers = format_modifiers_afbc_g12a; - ret = drm_universal_plane_init(priv->drm, plane, 0xFF, + ret = drm_universal_plane_init(&priv->drm, plane, 0xFF, &meson_plane_funcs, supported_drm_formats, ARRAY_SIZE(supported_drm_formats), format_modifiers, DRM_PLANE_TYPE_PRIMARY, "meson_primary_plane"); if (ret) { - devm_kfree(priv->drm->dev, meson_plane); + devm_kfree(priv->drm.dev, meson_plane); return ret; } -- 2.43.0

8 months

1
2
0 0

[PATCH v1 1/1] scsi: ufs: core: Fix the HIGH/LOW_TEMP Bit Definitions

by Bao D. Nguyen

According to the UFS Device Specification, the bUFSFeaturesSupport defines the support for TOO_HIGH_TEMPERATURE as bit[4] and the TOO_LOW_TEMPERATURE as bit[5]. Correct the code to match with the UFS device specification definition. Fixes: e88e2d322 ("scsi: ufs: core: Probe for temperature notification support") Cc: stable(a)vger.kernel.org Signed-off-by: Bao D. Nguyen <quic_nguyenb(a)quicinc.com> --- include/ufs/ufs.h | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/include/ufs/ufs.h b/include/ufs/ufs.h index e594abe..f0c6111 100644 --- a/include/ufs/ufs.h +++ b/include/ufs/ufs.h @@ -386,8 +386,8 @@ enum { /* Possible values for dExtendedUFSFeaturesSupport */ enum { - UFS_DEV_LOW_TEMP_NOTIF = BIT(4), - UFS_DEV_HIGH_TEMP_NOTIF = BIT(5), + UFS_DEV_HIGH_TEMP_NOTIF = BIT(4), + UFS_DEV_LOW_TEMP_NOTIF = BIT(5), UFS_DEV_EXT_TEMP_NOTIF = BIT(6), UFS_DEV_HPB_SUPPORT = BIT(7), UFS_DEV_WRITE_BOOSTER_SUP = BIT(8), -- 2.7.4

8 months

2
2
0 0

[PATCH v2 1/9] btrfs: fix double accounting race when btrfs_run_delalloc_range() failed

by Qu Wenruo

[BUG] When running btrfs with block size (4K) smaller than page size (64K, aarch64), there is a very high chance to crash the kernel at generic/750, with the following messages: (before the call traces, there are 3 extra debug messages added) BTRFS warning (device dm-3): read-write for sector size 4096 with page size 65536 is experimental BTRFS info (device dm-3): checking UUID tree hrtimer: interrupt took 5451385 ns BTRFS error (device dm-3): cow_file_range failed, root=4957 inode=257 start=1605632 len=69632: -28 BTRFS error (device dm-3): run_delalloc_nocow failed, root=4957 inode=257 start=1605632 len=69632: -28 BTRFS error (device dm-3): failed to run delalloc range, root=4957 ino=257 folio=1572864 submit_bitmap=8-15 start=1605632 len=69632: -28 ------------[ cut here ]------------ WARNING: CPU: 2 PID: 3020984 at ordered-data.c:360 can_finish_ordered_extent+0x370/0x3b8 [btrfs] CPU: 2 UID: 0 PID: 3020984 Comm: kworker/u24:1 Tainted: G OE 6.13.0-rc1-custom+ #89 Tainted: [O]=OOT_MODULE, [E]=UNSIGNED_MODULE Hardware name: QEMU KVM Virtual Machine, BIOS unknown 2/2/2022 Workqueue: events_unbound btrfs_async_reclaim_data_space [btrfs] pc : can_finish_ordered_extent+0x370/0x3b8 [btrfs] lr : can_finish_ordered_extent+0x1ec/0x3b8 [btrfs] Call trace: can_finish_ordered_extent+0x370/0x3b8 [btrfs] (P) can_finish_ordered_extent+0x1ec/0x3b8 [btrfs] (L) btrfs_mark_ordered_io_finished+0x130/0x2b8 [btrfs] extent_writepage+0x10c/0x3b8 [btrfs] extent_write_cache_pages+0x21c/0x4e8 [btrfs] btrfs_writepages+0x94/0x160 [btrfs] do_writepages+0x74/0x190 filemap_fdatawrite_wbc+0x74/0xa0 start_delalloc_inodes+0x17c/0x3b0 [btrfs] btrfs_start_delalloc_roots+0x17c/0x288 [btrfs] shrink_delalloc+0x11c/0x280 [btrfs] flush_space+0x288/0x328 [btrfs] btrfs_async_reclaim_data_space+0x180/0x228 [btrfs] process_one_work+0x228/0x680 worker_thread+0x1bc/0x360 kthread+0x100/0x118 ret_from_fork+0x10/0x20 ---[ end trace 0000000000000000 ]--- BTRFS critical (device dm-3): bad ordered extent accounting, root=4957 ino=257 OE offset=1605632 OE len=16384 to_dec=16384 left=0 BTRFS critical (device dm-3): bad ordered extent accounting, root=4957 ino=257 OE offset=1622016 OE len=12288 to_dec=12288 left=0 Unable to handle kernel NULL pointer dereference at virtual address 0000000000000008 BTRFS critical (device dm-3): bad ordered extent accounting, root=4957 ino=257 OE offset=1634304 OE len=8192 to_dec=4096 left=0 CPU: 1 UID: 0 PID: 3286940 Comm: kworker/u24:3 Tainted: G W OE 6.13.0-rc1-custom+ #89 Hardware name: QEMU KVM Virtual Machine, BIOS unknown 2/2/2022 Workqueue: btrfs_work_helper [btrfs] (btrfs-endio-write) pstate: 404000c5 (nZcv daIF +PAN -UAO -TCO -DIT -SSBS BTYPE=--) pc : process_one_work+0x110/0x680 lr : worker_thread+0x1bc/0x360 Call trace: process_one_work+0x110/0x680 (P) worker_thread+0x1bc/0x360 (L) worker_thread+0x1bc/0x360 kthread+0x100/0x118 ret_from_fork+0x10/0x20 Code: f84086a1 f9000fe1 53041c21 b9003361 (f9400661) ---[ end trace 0000000000000000 ]--- Kernel panic - not syncing: Oops: Fatal exception SMP: stopping secondary CPUs SMP: failed to stop secondary CPUs 2-3 Dumping ftrace buffer: (ftrace buffer empty) Kernel Offset: 0x275bb9540000 from 0xffff800080000000 PHYS_OFFSET: 0xffff8fbba0000000 CPU features: 0x100,00000070,00801250,8201720b [CAUSE] The above warning is triggered immediately after the delalloc range failure, this happens in the following sequence: - Range [1568K, 1636K) is dirty 1536K 1568K 1600K 1636K 1664K | |/////////|////////| | Where 1536K, 1600K and 1664K are page boundaries (64K page size) - Enter extent_writepage() for page 1536K - Enter run_delalloc_nocow() with locked page 1536K and range [1568K, 1636K) This is due to the inode has preallocated extents. - Enter cow_file_range() with locked page 1536K and range [1568K, 1636K) - btrfs_reserve_extent() only reserved two extents The main loop of cow_file_range() only reserved two data extents, Now we have: 1536K 1568K 1600K 1636K 1664K | |<-->|<--->|/|///////| | 1584K 1596K Range [1568K, 1596K) has ordered extent reserved. - btrfs_reserve_extent() failed inside cow_file_range() for file offset 1596K This is already a bug in our space reservation code, but for now let's focus on the error handling path. Now cow_file_range() returned -ENOSPC. - btrfs_run_delalloc_range() do error cleanup <<< ROOT CAUSE Call btrfs_cleanup_ordered_extents() with locked folio 1536K and range [1568K, 1636K) Function btrfs_cleanup_ordered_extents() normally needs to skip the ranges inside the folio, as it will normally be cleaned up by extent_writepage(). Such split error handling is already problematic in the first place. What's worse is the folio range skipping itself, which is not taking subpage cases into consideration at all, it will only skip the range if the page start >= the range start. In our case, the page start < the range start, since for subpage cases we can have delalloc ranges inside the folio but not covering the folio. So it doesn't skip the page range at all. This means all the ordered extents, both [1568K, 1584K) and [1584K, 1596K) will be marked as IOERR. And those two ordered extents have no more pending ios, it is marked finished, and *QUEUED* to be deleted from the io tree. - extent_writepage() do error cleanup Call btrfs_mark_ordered_io_finished() for the range [1536K, 1600K). Although ranges [1568K, 1584K) and [1584K, 1596K) are finished, the deletion from io tree is async, it may or may not happen at this timing. If the ranges are not yet removed, we will do double cleaning on those ranges, triggers the above ordered extent warnings. In theory there are other bugs, like the cleanup in extent_writepage() can cause double accounting on ranges that are submitted async (compression for example). But that's much harder to trigger because normally we do not mix regular and compression delalloc ranges. [FIX] The folio range split is already buggy and not subpage compatible, it's introduced a long time ago where subpage support is not even considered. So instead of splitting the ordered extents cleanup into the folio range and out of folio range, do all the cleanup inside writepage_delalloc(). - Pass @NULL as locked_folio for btrfs_cleanup_ordered_extents() in btrfs_run_delalloc_range() - Skip the btrfs_cleanup_ordered_extents() if writepage_delalloc() failed So all ordered extents are only cleaned up by btrfs_run_delalloc_range(). - Handle the ranges that already have ordered extents allocated If part of the folio already has ordered extent allocated, and btrfs_run_delalloc_range() failed, we also need to cleanup that range. Now we have a concentrated error handling for ordered extents during btrfs_run_delalloc_range(). Cc: stable(a)vger.kernel.org # 5.15+ Fixes: d1051d6ebf8e ("btrfs: Fix error handling in btrfs_cleanup_ordered_extents") Signed-off-by: Qu Wenruo <wqu(a)suse.com> --- fs/btrfs/extent_io.c | 37 ++++++++++++++++++++++++++++++++----- fs/btrfs/inode.c | 2 +- 2 files changed, 33 insertions(+), 6 deletions(-) diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c index 9725ff7f274d..417c710c55ca 100644 --- a/fs/btrfs/extent_io.c +++ b/fs/btrfs/extent_io.c @@ -1167,6 +1167,12 @@ static noinline_for_stack int writepage_delalloc(struct btrfs_inode *inode, * last delalloc end. */ u64 last_delalloc_end = 0; + /* + * Save the last successfully ran delalloc range end (exclusive). + * This is for error handling to avoid ranges with ordered extent created + * but no IO will be submitted due to error. + */ + u64 last_finished = page_start; u64 delalloc_start = page_start; u64 delalloc_end = page_end; u64 delalloc_to_write = 0; @@ -1235,11 +1241,19 @@ static noinline_for_stack int writepage_delalloc(struct btrfs_inode *inode, found_len = last_delalloc_end + 1 - found_start; if (ret >= 0) { + /* + * Some delalloc range may be created by previous folios. + * Thus we still need to clean those range up during error + * handling. + */ + last_finished = found_start; /* No errors hit so far, run the current delalloc range. */ ret = btrfs_run_delalloc_range(inode, folio, found_start, found_start + found_len - 1, wbc); + if (ret >= 0) + last_finished = found_start + found_len; } else { /* * We've hit an error during previous delalloc range, @@ -1274,8 +1288,21 @@ static noinline_for_stack int writepage_delalloc(struct btrfs_inode *inode, delalloc_start = found_start + found_len; } - if (ret < 0) + /* + * It's possible we have some ordered extents created before we hit + * an error, cleanup non-async successfully created delalloc ranges. + */ + if (unlikely(ret < 0)) { + unsigned int bitmap_size = min( + (last_finished - page_start) >> fs_info->sectorsize_bits, + fs_info->sectors_per_page); + + for_each_set_bit(bit, &bio_ctrl->submit_bitmap, bitmap_size) + btrfs_mark_ordered_io_finished(inode, folio, + page_start + (bit << fs_info->sectorsize_bits), + fs_info->sectorsize, false); return ret; + } out: if (last_delalloc_end) delalloc_end = last_delalloc_end; @@ -1509,13 +1536,13 @@ static int extent_writepage(struct folio *folio, struct btrfs_bio_ctrl *bio_ctrl bio_ctrl->wbc->nr_to_write--; -done: - if (ret) { + if (ret) btrfs_mark_ordered_io_finished(BTRFS_I(inode), folio, page_start, PAGE_SIZE, !ret); - mapping_set_error(folio->mapping, ret); - } +done: + if (ret < 0) + mapping_set_error(folio->mapping, ret); /* * Only unlock ranges that are submitted. As there can be some async * submitted ranges inside the folio. diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c index c4997200dbb2..d41bb47d59fb 100644 --- a/fs/btrfs/inode.c +++ b/fs/btrfs/inode.c @@ -2305,7 +2305,7 @@ int btrfs_run_delalloc_range(struct btrfs_inode *inode, struct folio *locked_fol out: if (ret < 0) - btrfs_cleanup_ordered_extents(inode, locked_folio, start, + btrfs_cleanup_ordered_extents(inode, NULL, start, end - start + 1); return ret; } -- 2.47.1

8 months, 1 week

3
3
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[PATCH] clk: clk-loongson2: Fix the number count of clk provider

by Binbin Zhou

Since commit 02fb4f008433 ("clk: clk-loongson2: Fix potential buffer overflow in flexible-array member access"), the clk provider register is failed. The count of `clks_num` is shown below: for (p = data; p->name; p++) clks_num++; In fact, `clks_num` represents the number of SoC clocks and should be expressed as the maximum value of the clock binding id in use (p->id + 1). Now we fix it to avoid the following error when trying to register a clk provider: [ 13.409595] of_clk_hw_onecell_get: invalid index 17 Fixes: 02fb4f008433 ("clk: clk-loongson2: Fix potential buffer overflow in flexible-array member access") Cc: stable(a)vger.kernel.org Signed-off-by: Binbin Zhou <zhoubinbin(a)loongson.cn> --- drivers/clk/clk-loongson2.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/clk/clk-loongson2.c b/drivers/clk/clk-loongson2.c index 6bf51d5a49a1..b1b2038acd0b 100644 --- a/drivers/clk/clk-loongson2.c +++ b/drivers/clk/clk-loongson2.c @@ -294,7 +294,7 @@ static int loongson2_clk_probe(struct platform_device *pdev) return -EINVAL; for (p = data; p->name; p++) - clks_num++; + clks_num = max(clks_num, p->id + 1); clp = devm_kzalloc(dev, struct_size(clp, clk_data.hws, clks_num), GFP_KERNEL); -- 2.43.5

8 months, 1 week

3
4
0 0

+ mm-zswap-properly-synchronize-freeing-resources-during-cpu-hotunplug.patch added to mm-hotfixes-unstable branch

by Andrew Morton

The patch titled Subject: mm: zswap: properly synchronize freeing resources during CPU hotunplug has been added to the -mm mm-hotfixes-unstable branch. Its filename is mm-zswap-properly-synchronize-freeing-resources-during-cpu-hotunplug.patch This patch will shortly appear at https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patche… This patch will later appear in the mm-hotfixes-unstable branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm Before you just go and hit "reply", please: a) Consider who else should be cc'ed b) Prefer to cc a suitable mailing list as well c) Ideally: find the original patch on the mailing list and do a reply-to-all to that, adding suitable additional cc's *** Remember to use Documentation/process/submit-checklist.rst when testing your code *** The -mm tree is included into linux-next via the mm-everything branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm and is updated there every 2-3 working days ------------------------------------------------------ From: Yosry Ahmed <yosryahmed(a)google.com> Subject: mm: zswap: properly synchronize freeing resources during CPU hotunplug Date: Wed, 8 Jan 2025 22:24:41 +0000 In zswap_compress() and zswap_decompress(), the per-CPU acomp_ctx of the current CPU at the beginning of the operation is retrieved and used throughout. However, since neither preemption nor migration are disabled, it is possible that the operation continues on a different CPU. If the original CPU is hotunplugged while the acomp_ctx is still in use, we run into a UAF bug as some of the resources attached to the acomp_ctx are freed during hotunplug in zswap_cpu_comp_dead() (i.e. acomp_ctx.buffer, acomp_ctx.req, or acomp_ctx.acomp). The problem was introduced in commit 1ec3b5fe6eec ("mm/zswap: move to use crypto_acomp API for hardware acceleration") when the switch to the crypto_acomp API was made. Prior to that, the per-CPU crypto_comp was retrieved using get_cpu_ptr() which disables preemption and makes sure the CPU cannot go away from under us. Preemption cannot be disabled with the crypto_acomp API as a sleepable context is needed. Use the acomp_ctx.mutex to synchronize CPU hotplug callbacks allocating and freeing resources with compression/decompression paths. Make sure that acomp_ctx.req is NULL when the resources are freed. In the compression/decompression paths, check if acomp_ctx.req is NULL after acquiring the mutex (meaning the CPU was offlined) and retry on the new CPU. The initialization of acomp_ctx.mutex is moved from the CPU hotplug callback to the pool initialization where it belongs (where the mutex is allocated). In addition to adding clarity, this makes sure that CPU hotplug cannot reinitialize a mutex that is already locked by compression/decompression. Previously a fix was attempted by holding cpus_read_lock() [1]. This would have caused a potential deadlock as it is possible for code already holding the lock to fall into reclaim and enter zswap (causing a deadlock). A fix was also attempted using SRCU for synchronization, but Johannes pointed out that synchronize_srcu() cannot be used in CPU hotplug notifiers [2]. Alternative fixes that were considered/attempted and could have worked: - Refcounting the per-CPU acomp_ctx. This involves complexity in handling the race between the refcount dropping to zero in zswap_[de]compress() and the refcount being re-initialized when the CPU is onlined. - Disabling migration before getting the per-CPU acomp_ctx [3], but that's discouraged and is a much bigger hammer than needed, and could result in subtle performance issues. [1]https://lkml.kernel.org/20241219212437.2714151-1-yosryahmed@google.com/ [2]https://lkml.kernel.org/20250107074724.1756696-2-yosryahmed@google.com/ [3]https://lkml.kernel.org/20250107222236.2715883-2-yosryahmed@google.com/ Link: https://lkml.kernel.org/r/20250108222441.3622031-1-yosryahmed@google.com Fixes: 1ec3b5fe6eec ("mm/zswap: move to use crypto_acomp API for hardware acceleration") Signed-off-by: Yosry Ahmed <yosryahmed(a)google.com> Reported-by: Johannes Weiner <hannes(a)cmpxchg.org> Closes: https://lore.kernel.org/lkml/20241113213007.GB1564047@cmpxchg.org/ Reported-by: Sam Sun <samsun1006219(a)gmail.com> Closes: https://lore.kernel.org/lkml/CAEkJfYMtSdM5HceNsXUDf5haghD5+o2e7Qv4OcuruL4tP… Cc: Barry Song <baohua(a)kernel.org> Cc: Chengming Zhou <chengming.zhou(a)linux.dev> Cc: Kanchana P Sridhar <kanchana.p.sridhar(a)intel.com> Cc: Nhat Pham <nphamcs(a)gmail.com> Cc: Vitaly Wool <vitalywool(a)gmail.com> Cc: <stable(a)vger.kernel.org> Signed-off-by: Andrew Morton <akpm(a)linux-foundation.org> --- mm/zswap.c | 60 +++++++++++++++++++++++++++++++++++++++------------ 1 file changed, 46 insertions(+), 14 deletions(-) --- a/mm/zswap.c~mm-zswap-properly-synchronize-freeing-resources-during-cpu-hotunplug +++ a/mm/zswap.c @@ -251,7 +251,7 @@ static struct zswap_pool *zswap_pool_cre struct zswap_pool *pool; char name[38]; /* 'zswap' + 32 char (max) num + \0 */ gfp_t gfp = __GFP_NORETRY | __GFP_NOWARN | __GFP_KSWAPD_RECLAIM; - int ret; + int ret, cpu; if (!zswap_has_pool) { /* if either are unset, pool initialization failed, and we @@ -285,6 +285,9 @@ static struct zswap_pool *zswap_pool_cre goto error; } + for_each_possible_cpu(cpu) + mutex_init(&per_cpu_ptr(pool->acomp_ctx, cpu)->mutex); + ret = cpuhp_state_add_instance(CPUHP_MM_ZSWP_POOL_PREPARE, &pool->node); if (ret) @@ -821,11 +824,12 @@ static int zswap_cpu_comp_prepare(unsign struct acomp_req *req; int ret; - mutex_init(&acomp_ctx->mutex); - + mutex_lock(&acomp_ctx->mutex); acomp_ctx->buffer = kmalloc_node(PAGE_SIZE * 2, GFP_KERNEL, cpu_to_node(cpu)); - if (!acomp_ctx->buffer) - return -ENOMEM; + if (!acomp_ctx->buffer) { + ret = -ENOMEM; + goto buffer_fail; + } acomp = crypto_alloc_acomp_node(pool->tfm_name, 0, 0, cpu_to_node(cpu)); if (IS_ERR(acomp)) { @@ -844,6 +848,8 @@ static int zswap_cpu_comp_prepare(unsign ret = -ENOMEM; goto req_fail; } + + /* acomp_ctx->req must be NULL if the acomp_ctx is not fully initialized */ acomp_ctx->req = req; crypto_init_wait(&acomp_ctx->wait); @@ -855,12 +861,15 @@ static int zswap_cpu_comp_prepare(unsign acomp_request_set_callback(req, CRYPTO_TFM_REQ_MAY_BACKLOG, crypto_req_done, &acomp_ctx->wait); + mutex_unlock(&acomp_ctx->mutex); return 0; req_fail: crypto_free_acomp(acomp_ctx->acomp); acomp_fail: kfree(acomp_ctx->buffer); +buffer_fail: + mutex_unlock(&acomp_ctx->mutex); return ret; } @@ -869,17 +878,45 @@ static int zswap_cpu_comp_dead(unsigned struct zswap_pool *pool = hlist_entry(node, struct zswap_pool, node); struct crypto_acomp_ctx *acomp_ctx = per_cpu_ptr(pool->acomp_ctx, cpu); + mutex_lock(&acomp_ctx->mutex); if (!IS_ERR_OR_NULL(acomp_ctx)) { if (!IS_ERR_OR_NULL(acomp_ctx->req)) acomp_request_free(acomp_ctx->req); + acomp_ctx->req = NULL; if (!IS_ERR_OR_NULL(acomp_ctx->acomp)) crypto_free_acomp(acomp_ctx->acomp); kfree(acomp_ctx->buffer); } + mutex_unlock(&acomp_ctx->mutex); return 0; } +static struct crypto_acomp_ctx *acomp_ctx_get_cpu_lock(struct zswap_pool *pool) +{ + struct crypto_acomp_ctx *acomp_ctx; + + for (;;) { + acomp_ctx = raw_cpu_ptr(pool->acomp_ctx); + mutex_lock(&acomp_ctx->mutex); + if (likely(acomp_ctx->req)) + return acomp_ctx; + /* + * It is possible that we were migrated to a different CPU after + * getting the per-CPU ctx but before the mutex was acquired. If + * the old CPU got offlined, zswap_cpu_comp_dead() could have + * already freed ctx->req (among other things) and set it to + * NULL. Just try again on the new CPU that we ended up on. + */ + mutex_unlock(&acomp_ctx->mutex); + } +} + +static void acomp_ctx_put_unlock(struct crypto_acomp_ctx *acomp_ctx) +{ + mutex_unlock(&acomp_ctx->mutex); +} + static bool zswap_compress(struct page *page, struct zswap_entry *entry, struct zswap_pool *pool) { @@ -893,10 +930,7 @@ static bool zswap_compress(struct page * gfp_t gfp; u8 *dst; - acomp_ctx = raw_cpu_ptr(pool->acomp_ctx); - - mutex_lock(&acomp_ctx->mutex); - + acomp_ctx = acomp_ctx_get_cpu_lock(pool); dst = acomp_ctx->buffer; sg_init_table(&input, 1); sg_set_page(&input, page, PAGE_SIZE, 0); @@ -949,7 +983,7 @@ unlock: else if (alloc_ret) zswap_reject_alloc_fail++; - mutex_unlock(&acomp_ctx->mutex); + acomp_ctx_put_unlock(acomp_ctx); return comp_ret == 0 && alloc_ret == 0; } @@ -960,9 +994,7 @@ static void zswap_decompress(struct zswa struct crypto_acomp_ctx *acomp_ctx; u8 *src; - acomp_ctx = raw_cpu_ptr(entry->pool->acomp_ctx); - mutex_lock(&acomp_ctx->mutex); - + acomp_ctx = acomp_ctx_get_cpu_lock(entry->pool); src = zpool_map_handle(zpool, entry->handle, ZPOOL_MM_RO); /* * If zpool_map_handle is atomic, we cannot reliably utilize its mapped buffer @@ -986,10 +1018,10 @@ static void zswap_decompress(struct zswa acomp_request_set_params(acomp_ctx->req, &input, &output, entry->length, PAGE_SIZE); BUG_ON(crypto_wait_req(crypto_acomp_decompress(acomp_ctx->req), &acomp_ctx->wait)); BUG_ON(acomp_ctx->req->dlen != PAGE_SIZE); - mutex_unlock(&acomp_ctx->mutex); if (src != acomp_ctx->buffer) zpool_unmap_handle(zpool, entry->handle); + acomp_ctx_put_unlock(acomp_ctx); } /********************************* _ Patches currently in -mm which might be from yosryahmed(a)google.com are revert-mm-zswap-fix-race-between-compression-and-cpu-hotunplug.patch mm-zswap-properly-synchronize-freeing-resources-during-cpu-hotunplug.patch mm-zswap-properly-synchronize-freeing-resources-during-cpu-hotunplug-fix.patch

8 months, 1 week

1
0
0 0

[PATCH v2] mm: zswap: properly synchronize freeing resources during CPU hotunplug

by Yosry Ahmed

In zswap_compress() and zswap_decompress(), the per-CPU acomp_ctx of the current CPU at the beginning of the operation is retrieved and used throughout. However, since neither preemption nor migration are disabled, it is possible that the operation continues on a different CPU. If the original CPU is hotunplugged while the acomp_ctx is still in use, we run into a UAF bug as some of the resources attached to the acomp_ctx are freed during hotunplug in zswap_cpu_comp_dead() (i.e. acomp_ctx.buffer, acomp_ctx.req, or acomp_ctx.acomp). The problem was introduced in commit 1ec3b5fe6eec ("mm/zswap: move to use crypto_acomp API for hardware acceleration") when the switch to the crypto_acomp API was made. Prior to that, the per-CPU crypto_comp was retrieved using get_cpu_ptr() which disables preemption and makes sure the CPU cannot go away from under us. Preemption cannot be disabled with the crypto_acomp API as a sleepable context is needed. Use the acomp_ctx.mutex to synchronize CPU hotplug callbacks allocating and freeing resources with compression/decompression paths. Make sure that acomp_ctx.req is NULL when the resources are freed. In the compression/decompression paths, check if acomp_ctx.req is NULL after acquiring the mutex (meaning the CPU was offlined) and retry on the new CPU. The initialization of acomp_ctx.mutex is moved from the CPU hotplug callback to the pool initialization where it belongs (where the mutex is allocated). In addition to adding clarity, this makes sure that CPU hotplug cannot reinitialize a mutex that is already locked by compression/decompression. Previously a fix was attempted by holding cpus_read_lock() [1]. This would have caused a potential deadlock as it is possible for code already holding the lock to fall into reclaim and enter zswap (causing a deadlock). A fix was also attempted using SRCU for synchronization, but Johannes pointed out that synchronize_srcu() cannot be used in CPU hotplug notifiers [2]. Alternative fixes that were considered/attempted and could have worked: - Refcounting the per-CPU acomp_ctx. This involves complexity in handling the race between the refcount dropping to zero in zswap_[de]compress() and the refcount being re-initialized when the CPU is onlined. - Disabling migration before getting the per-CPU acomp_ctx [3], but that's discouraged and is a much bigger hammer than needed, and could result in subtle performance issues. [1]https://lkml.kernel.org/20241219212437.2714151-1-yosryahmed@google.com/ [2]https://lkml.kernel.org/20250107074724.1756696-2-yosryahmed@google.com/ [3]https://lkml.kernel.org/20250107222236.2715883-2-yosryahmed@google.com/ Fixes: 1ec3b5fe6eec ("mm/zswap: move to use crypto_acomp API for hardware acceleration") Cc: <stable(a)vger.kernel.org> Signed-off-by: Yosry Ahmed <yosryahmed(a)google.com> Reported-by: Johannes Weiner <hannes(a)cmpxchg.org> Closes: https://lore.kernel.org/lkml/20241113213007.GB1564047@cmpxchg.org/ Reported-by: Sam Sun <samsun1006219(a)gmail.com> Closes: https://lore.kernel.org/lkml/CAEkJfYMtSdM5HceNsXUDf5haghD5+o2e7Qv4OcuruL4tP… --- This applies on top of the latest mm-hotfixes-unstable on top of 'Revert "mm: zswap: fix race between [de]compression and CPU hotunplug"' and after 'mm: zswap: disable migration while using per-CPU acomp_ctx' was dropped. v1 -> v2: - Move the initialization of the mutex to pool initialization. - Use the mutex to also synchronize with the CPU hotplug callback (i.e. zswap_cpu_comp_prep()). - Naming cleanups. --- mm/zswap.c | 60 +++++++++++++++++++++++++++++++++++++++++------------- 1 file changed, 46 insertions(+), 14 deletions(-) diff --git a/mm/zswap.c b/mm/zswap.c index f6316b66fb236..4d7e564732267 100644 --- a/mm/zswap.c +++ b/mm/zswap.c @@ -251,7 +251,7 @@ static struct zswap_pool *zswap_pool_create(char *type, char *compressor) struct zswap_pool *pool; char name[38]; /* 'zswap' + 32 char (max) num + \0 */ gfp_t gfp = __GFP_NORETRY | __GFP_NOWARN | __GFP_KSWAPD_RECLAIM; - int ret; + int ret, cpu; if (!zswap_has_pool) { /* if either are unset, pool initialization failed, and we @@ -285,6 +285,9 @@ static struct zswap_pool *zswap_pool_create(char *type, char *compressor) goto error; } + for_each_possible_cpu(cpu) + mutex_init(&per_cpu_ptr(pool->acomp_ctx, cpu)->mutex); + ret = cpuhp_state_add_instance(CPUHP_MM_ZSWP_POOL_PREPARE, &pool->node); if (ret) @@ -821,11 +824,12 @@ static int zswap_cpu_comp_prepare(unsigned int cpu, struct hlist_node *node) struct acomp_req *req; int ret; - mutex_init(&acomp_ctx->mutex); - + mutex_lock(&acomp_ctx->mutex); acomp_ctx->buffer = kmalloc_node(PAGE_SIZE * 2, GFP_KERNEL, cpu_to_node(cpu)); - if (!acomp_ctx->buffer) - return -ENOMEM; + if (!acomp_ctx->buffer) { + ret = -ENOMEM; + goto buffer_fail; + } acomp = crypto_alloc_acomp_node(pool->tfm_name, 0, 0, cpu_to_node(cpu)); if (IS_ERR(acomp)) { @@ -844,6 +848,8 @@ static int zswap_cpu_comp_prepare(unsigned int cpu, struct hlist_node *node) ret = -ENOMEM; goto req_fail; } + + /* acomp_ctx->req must be NULL if the acomp_ctx is not fully initialized */ acomp_ctx->req = req; crypto_init_wait(&acomp_ctx->wait); @@ -855,12 +861,15 @@ static int zswap_cpu_comp_prepare(unsigned int cpu, struct hlist_node *node) acomp_request_set_callback(req, CRYPTO_TFM_REQ_MAY_BACKLOG, crypto_req_done, &acomp_ctx->wait); + mutex_unlock(&acomp_ctx->mutex); return 0; req_fail: crypto_free_acomp(acomp_ctx->acomp); acomp_fail: kfree(acomp_ctx->buffer); +buffer_fail: + mutex_unlock(&acomp_ctx->mutex); return ret; } @@ -869,17 +878,45 @@ static int zswap_cpu_comp_dead(unsigned int cpu, struct hlist_node *node) struct zswap_pool *pool = hlist_entry(node, struct zswap_pool, node); struct crypto_acomp_ctx *acomp_ctx = per_cpu_ptr(pool->acomp_ctx, cpu); + mutex_lock(&acomp_ctx->mutex); if (!IS_ERR_OR_NULL(acomp_ctx)) { if (!IS_ERR_OR_NULL(acomp_ctx->req)) acomp_request_free(acomp_ctx->req); + acomp_ctx->req = NULL; if (!IS_ERR_OR_NULL(acomp_ctx->acomp)) crypto_free_acomp(acomp_ctx->acomp); kfree(acomp_ctx->buffer); } + mutex_unlock(&acomp_ctx->mutex); return 0; } +static struct crypto_acomp_ctx *acomp_ctx_get_cpu_lock(struct zswap_pool *pool) +{ + struct crypto_acomp_ctx *acomp_ctx; + + for (;;) { + acomp_ctx = raw_cpu_ptr(pool->acomp_ctx); + mutex_lock(&acomp_ctx->mutex); + if (likely(acomp_ctx->req)) + return acomp_ctx; + /* + * It is possible that we were migrated to a different CPU after + * getting the per-CPU ctx but before the mutex was acquired. If + * the old CPU got offlined, zswap_cpu_comp_dead() could have + * already freed ctx->req (among other things) and set it to + * NULL. Just try again on the new CPU that we ended up on. + */ + mutex_unlock(&acomp_ctx->mutex); + } +} + +static void acomp_ctx_put_unlock(struct crypto_acomp_ctx *acomp_ctx) +{ + mutex_unlock(&acomp_ctx->mutex); +} + static bool zswap_compress(struct page *page, struct zswap_entry *entry, struct zswap_pool *pool) { @@ -893,10 +930,7 @@ static bool zswap_compress(struct page *page, struct zswap_entry *entry, gfp_t gfp; u8 *dst; - acomp_ctx = raw_cpu_ptr(pool->acomp_ctx); - - mutex_lock(&acomp_ctx->mutex); - + acomp_ctx = acomp_ctx_get_cpu_lock(pool); dst = acomp_ctx->buffer; sg_init_table(&input, 1); sg_set_page(&input, page, PAGE_SIZE, 0); @@ -949,7 +983,7 @@ static bool zswap_compress(struct page *page, struct zswap_entry *entry, else if (alloc_ret) zswap_reject_alloc_fail++; - mutex_unlock(&acomp_ctx->mutex); + acomp_ctx_put_unlock(acomp_ctx); return comp_ret == 0 && alloc_ret == 0; } @@ -960,9 +994,7 @@ static void zswap_decompress(struct zswap_entry *entry, struct folio *folio) struct crypto_acomp_ctx *acomp_ctx; u8 *src; - acomp_ctx = raw_cpu_ptr(entry->pool->acomp_ctx); - mutex_lock(&acomp_ctx->mutex); - + acomp_ctx = acomp_ctx_get_cpu_lock(entry->pool); src = zpool_map_handle(zpool, entry->handle, ZPOOL_MM_RO); /* * If zpool_map_handle is atomic, we cannot reliably utilize its mapped buffer @@ -986,10 +1018,10 @@ static void zswap_decompress(struct zswap_entry *entry, struct folio *folio) acomp_request_set_params(acomp_ctx->req, &input, &output, entry->length, PAGE_SIZE); BUG_ON(crypto_wait_req(crypto_acomp_decompress(acomp_ctx->req), &acomp_ctx->wait)); BUG_ON(acomp_ctx->req->dlen != PAGE_SIZE); - mutex_unlock(&acomp_ctx->mutex); if (src != acomp_ctx->buffer) zpool_unmap_handle(zpool, entry->handle); + acomp_ctx_put_unlock(acomp_ctx); } /********************************* -- 2.47.1.613.gc27f4b7a9f-goog

8 months, 1 week

2
2
0 0

[PATCH] mm: zswap: properly synchronize freeing resources during CPU hotunplug

by Yosry Ahmed

In zswap_compress() and zswap_decompress(), the per-CPU acomp_ctx of the current CPU at the beginning of the operation is retrieved and used throughout. However, since neither preemption nor migration are disabled, it is possible that the operation continues on a different CPU. If the original CPU is hotunplugged while the acomp_ctx is still in use, we run into a UAF bug as some of the resources attached to the acomp_ctx are freed during hotunplug in zswap_cpu_comp_dead(). The problem was introduced in commit 1ec3b5fe6eec ("mm/zswap: move to use crypto_acomp API for hardware acceleration") when the switch to the crypto_acomp API was made. Prior to that, the per-CPU crypto_comp was retrieved using get_cpu_ptr() which disables preemption and makes sure the CPU cannot go away from under us. Preemption cannot be disabled with the crypto_acomp API as a sleepable context is needed. During CPU hotunplug, hold the acomp_ctx.mutex before freeing any resources, and set acomp_ctx.req to NULL when it is freed. In the compress/decompress paths, after acquiring the acomp_ctx.mutex make sure that acomp_ctx.req is not NULL (i.e. acomp_ctx resources were not freed by CPU hotunplug). Otherwise, retry with the acomp_ctx from the new CPU. This adds proper synchronization to ensure that the acomp_ctx resources are not freed from under compress/decompress paths. Note that the per-CPU acomp_ctx itself (including the mutex) is not freed during CPU hotunplug, only acomp_ctx.req, acomp_ctx.buffer, and acomp_ctx.acomp. So it is safe to acquire the acomp_ctx.mutex of a CPU after it is hotunplugged. Previously a fix was attempted by holding cpus_read_lock() [1]. This would have caused a potential deadlock as it is possible for code already holding the lock to fall into reclaim and enter zswap (causing a deadlock). A fix was also attempted using SRCU for synchronization, but Johannes pointed out that synchronize_srcu() cannot be used in CPU hotplug notifiers [2]. Alternative fixes that were considered/attempted and could have worked: - Refcounting the per-CPU acomp_ctx. This involves complexity in handling the race between the refcount dropping to zero in zswap_[de]compress() and the refcount being re-initialized when the CPU is onlined. - Disabling migration before getting the per-CPU acomp_ctx [3], but that's discouraged and is a much bigger hammer than needed, and could result in subtle performance issues. [1]https://lkml.kernel.org/20241219212437.2714151-1-yosryahmed@google.com/ [2]https://lkml.kernel.org/20250107074724.1756696-2-yosryahmed@google.com/ [3]https://lkml.kernel.org/20250107222236.2715883-2-yosryahmed@google.com/ Fixes: 1ec3b5fe6eec ("mm/zswap: move to use crypto_acomp API for hardware acceleration") Cc: <stable(a)vger.kernel.org> Signed-off-by: Yosry Ahmed <yosryahmed(a)google.com> Reported-by: Johannes Weiner <hannes(a)cmpxchg.org> Closes: https://lore.kernel.org/lkml/20241113213007.GB1564047@cmpxchg.org/ Reported-by: Sam Sun <samsun1006219(a)gmail.com> Closes: https://lore.kernel.org/lkml/CAEkJfYMtSdM5HceNsXUDf5haghD5+o2e7Qv4OcuruL4tP… --- This applies on top of the latest mm-hotfixes-unstable on top of 'Revert "mm: zswap: fix race between [de]compression and CPU hotunplug"' and after 'mm: zswap: disable migration while using per-CPU acomp_ctx' was dropped. --- mm/zswap.c | 42 +++++++++++++++++++++++++++++++++--------- 1 file changed, 33 insertions(+), 9 deletions(-) diff --git a/mm/zswap.c b/mm/zswap.c index f6316b66fb236..4e3148050e093 100644 --- a/mm/zswap.c +++ b/mm/zswap.c @@ -869,17 +869,46 @@ static int zswap_cpu_comp_dead(unsigned int cpu, struct hlist_node *node) struct zswap_pool *pool = hlist_entry(node, struct zswap_pool, node); struct crypto_acomp_ctx *acomp_ctx = per_cpu_ptr(pool->acomp_ctx, cpu); + mutex_lock(&acomp_ctx->mutex); if (!IS_ERR_OR_NULL(acomp_ctx)) { if (!IS_ERR_OR_NULL(acomp_ctx->req)) acomp_request_free(acomp_ctx->req); + acomp_ctx->req = NULL; if (!IS_ERR_OR_NULL(acomp_ctx->acomp)) crypto_free_acomp(acomp_ctx->acomp); kfree(acomp_ctx->buffer); } + mutex_unlock(&acomp_ctx->mutex); return 0; } +static struct crypto_acomp_ctx *acomp_ctx_get_cpu_lock( + struct crypto_acomp_ctx __percpu *acomp_ctx) +{ + struct crypto_acomp_ctx *ctx; + + for (;;) { + ctx = raw_cpu_ptr(acomp_ctx); + mutex_lock(&ctx->mutex); + if (likely(ctx->req)) + return ctx; + /* + * It is possible that we were migrated to a different CPU after + * getting the per-CPU ctx but before the mutex was acquired. If + * the old CPU got offlined, zswap_cpu_comp_dead() could have + * already freed ctx->req (among other things) and set it to + * NULL. Just try again on the new CPU that we ended up on. + */ + mutex_unlock(&ctx->mutex); + } +} + +static void acomp_ctx_put_unlock(struct crypto_acomp_ctx *ctx) +{ + mutex_unlock(&ctx->mutex); +} + static bool zswap_compress(struct page *page, struct zswap_entry *entry, struct zswap_pool *pool) { @@ -893,10 +922,7 @@ static bool zswap_compress(struct page *page, struct zswap_entry *entry, gfp_t gfp; u8 *dst; - acomp_ctx = raw_cpu_ptr(pool->acomp_ctx); - - mutex_lock(&acomp_ctx->mutex); - + acomp_ctx = acomp_ctx_get_cpu_lock(pool->acomp_ctx); dst = acomp_ctx->buffer; sg_init_table(&input, 1); sg_set_page(&input, page, PAGE_SIZE, 0); @@ -949,7 +975,7 @@ static bool zswap_compress(struct page *page, struct zswap_entry *entry, else if (alloc_ret) zswap_reject_alloc_fail++; - mutex_unlock(&acomp_ctx->mutex); + acomp_ctx_put_unlock(acomp_ctx); return comp_ret == 0 && alloc_ret == 0; } @@ -960,9 +986,7 @@ static void zswap_decompress(struct zswap_entry *entry, struct folio *folio) struct crypto_acomp_ctx *acomp_ctx; u8 *src; - acomp_ctx = raw_cpu_ptr(entry->pool->acomp_ctx); - mutex_lock(&acomp_ctx->mutex); - + acomp_ctx = acomp_ctx_get_cpu_lock(entry->pool->acomp_ctx); src = zpool_map_handle(zpool, entry->handle, ZPOOL_MM_RO); /* * If zpool_map_handle is atomic, we cannot reliably utilize its mapped buffer @@ -986,10 +1010,10 @@ static void zswap_decompress(struct zswap_entry *entry, struct folio *folio) acomp_request_set_params(acomp_ctx->req, &input, &output, entry->length, PAGE_SIZE); BUG_ON(crypto_wait_req(crypto_acomp_decompress(acomp_ctx->req), &acomp_ctx->wait)); BUG_ON(acomp_ctx->req->dlen != PAGE_SIZE); - mutex_unlock(&acomp_ctx->mutex); if (src != acomp_ctx->buffer) zpool_unmap_handle(zpool, entry->handle); + acomp_ctx_put_unlock(acomp_ctx); } /********************************* -- 2.47.1.613.gc27f4b7a9f-goog

8 months, 1 week

3
3
0 0

[PATCH 6.6.y 1/2] erofs: handle overlapped pclusters out of crafted images properly

by Gao Xiang

commit 9e2f9d34dd12e6e5b244ec488bcebd0c2d566c50 upstream. syzbot reported a task hang issue due to a deadlock case where it is waiting for the folio lock of a cached folio that will be used for cache I/Os. After looking into the crafted fuzzed image, I found it's formed with several overlapped big pclusters as below: Ext: logical offset | length : physical offset | length 0: 0.. 16384 | 16384 : 151552.. 167936 | 16384 1: 16384.. 32768 | 16384 : 155648.. 172032 | 16384 2: 32768.. 49152 | 16384 : 537223168.. 537239552 | 16384 ... Here, extent 0/1 are physically overlapped although it's entirely _impossible_ for normal filesystem images generated by mkfs. First, managed folios containing compressed data will be marked as up-to-date and then unlocked immediately (unlike in-place folios) when compressed I/Os are complete. If physical blocks are not submitted in the incremental order, there should be separate BIOs to avoid dependency issues. However, the current code mis-arranges z_erofs_fill_bio_vec() and BIO submission which causes unexpected BIO waits. Second, managed folios will be connected to their own pclusters for efficient inter-queries. However, this is somewhat hard to implement easily if overlapped big pclusters exist. Again, these only appear in fuzzed images so let's simply fall back to temporary short-lived pages for correctness. Additionally, it justifies that referenced managed folios cannot be truncated for now and reverts part of commit 2080ca1ed3e4 ("erofs: tidy up `struct z_erofs_bvec`") for simplicity although it shouldn't be any difference. Reported-by: syzbot+4fc98ed414ae63d1ada2(a)syzkaller.appspotmail.com Reported-by: syzbot+de04e06b28cfecf2281c(a)syzkaller.appspotmail.com Reported-by: syzbot+c8c8238b394be4a1087d(a)syzkaller.appspotmail.com Tested-by: syzbot+4fc98ed414ae63d1ada2(a)syzkaller.appspotmail.com Closes: https://lore.kernel.org/r/0000000000002fda01061e334873@google.com Fixes: 8e6c8fa9f2e9 ("erofs: enable big pcluster feature") Link: https://lore.kernel.org/r/20240910070847.3356592-1-hsiangkao@linux.alibaba.… Signed-off-by: Gao Xiang <hsiangkao(a)linux.alibaba.com> --- fs/erofs/zdata.c | 59 +++++++++++++++++++++++++----------------------- 1 file changed, 31 insertions(+), 28 deletions(-) diff --git a/fs/erofs/zdata.c b/fs/erofs/zdata.c index 1c0e6167d8e7..9fa07436a4da 100644 --- a/fs/erofs/zdata.c +++ b/fs/erofs/zdata.c @@ -1483,14 +1483,13 @@ static struct page *pickup_page_for_submission(struct z_erofs_pcluster *pcl, goto out; lock_page(page); - - /* only true if page reclaim goes wrong, should never happen */ - DBG_BUGON(justfound && PagePrivate(page)); - - /* the page is still in manage cache */ - if (page->mapping == mc) { + if (likely(page->mapping == mc)) { WRITE_ONCE(pcl->compressed_bvecs[nr].page, page); + /* + * The cached folio is still in managed cache but without + * a valid `->private` pcluster hint. Let's reconnect them. + */ if (!PagePrivate(page)) { /* * impossible to be !PagePrivate(page) for @@ -1504,22 +1503,24 @@ static struct page *pickup_page_for_submission(struct z_erofs_pcluster *pcl, SetPagePrivate(page); } - /* no need to submit io if it is already up-to-date */ - if (PageUptodate(page)) { - unlock_page(page); - page = NULL; + if (likely(page->private == (unsigned long)pcl)) { + /* don't submit cache I/Os again if already uptodate */ + if (PageUptodate(page)) { + unlock_page(page); + page = NULL; + + } + goto out; } - goto out; + /* + * Already linked with another pcluster, which only appears in + * crafted images by fuzzers for now. But handle this anyway. + */ + tocache = false; /* use temporary short-lived pages */ + } else { + DBG_BUGON(1); /* referenced managed folios can't be truncated */ + tocache = true; } - - /* - * the managed page has been truncated, it's unsafe to - * reuse this one, let's allocate a new cache-managed page. - */ - DBG_BUGON(page->mapping); - DBG_BUGON(!justfound); - - tocache = true; unlock_page(page); put_page(page); out_allocpage: @@ -1677,16 +1678,11 @@ static void z_erofs_submit_queue(struct z_erofs_decompress_frontend *f, end = cur + pcl->pclusterpages; do { - struct page *page; - - page = pickup_page_for_submission(pcl, i++, - &f->pagepool, mc); - if (!page) - continue; + struct page *page = NULL; if (bio && (cur != last_index + 1 || last_bdev != mdev.m_bdev)) { -submit_bio_retry: +drain_io: submit_bio(bio); if (memstall) { psi_memstall_leave(&pflags); @@ -1695,6 +1691,13 @@ static void z_erofs_submit_queue(struct z_erofs_decompress_frontend *f, bio = NULL; } + if (!page) { + page = pickup_page_for_submission(pcl, i++, + &f->pagepool, mc); + if (!page) + continue; + } + if (unlikely(PageWorkingset(page)) && !memstall) { psi_memstall_enter(&pflags); memstall = 1; @@ -1715,7 +1718,7 @@ static void z_erofs_submit_queue(struct z_erofs_decompress_frontend *f, } if (bio_add_page(bio, page, PAGE_SIZE, 0) < PAGE_SIZE) - goto submit_bio_retry; + goto drain_io; last_index = cur; bypass = false; -- 2.43.5

8 months, 1 week

2
2
0 0

[PATCH 5.10-6.1] ceph: give up on paths longer than PATH_MAX

by Ilya Dryomov

From: Max Kellermann <max.kellermann(a)ionos.com> commit 550f7ca98ee028a606aa75705a7e77b1bd11720f upstream. If the full path to be built by ceph_mdsc_build_path() happens to be longer than PATH_MAX, then this function will enter an endless (retry) loop, effectively blocking the whole task. Most of the machine becomes unusable, making this a very simple and effective DoS vulnerability. I cannot imagine why this retry was ever implemented, but it seems rather useless and harmful to me. Let's remove it and fail with ENAMETOOLONG instead. Cc: stable(a)vger.kernel.org Reported-by: Dario Weißer <dario(a)cure53.de> Signed-off-by: Max Kellermann <max.kellermann(a)ionos.com> Reviewed-by: Alex Markuze <amarkuze(a)redhat.com> Signed-off-by: Ilya Dryomov <idryomov(a)gmail.com> [idryomov(a)gmail.com: backport to 6.1: pr_warn() is still in use] --- fs/ceph/mds_client.c | 9 ++++----- 1 file changed, 4 insertions(+), 5 deletions(-) diff --git a/fs/ceph/mds_client.c b/fs/ceph/mds_client.c index da9fcf48ab6c..741ca7d10032 100644 --- a/fs/ceph/mds_client.c +++ b/fs/ceph/mds_client.c @@ -2447,12 +2447,11 @@ char *ceph_mdsc_build_path(struct dentry *dentry, int *plen, u64 *pbase, if (pos < 0) { /* - * A rename didn't occur, but somehow we didn't end up where - * we thought we would. Throw a warning and try again. + * The path is longer than PATH_MAX and this function + * cannot ever succeed. Creating paths that long is + * possible with Ceph, but Linux cannot use them. */ - pr_warn("build_path did not end path lookup where " - "expected, pos is %d\n", pos); - goto retry; + return ERR_PTR(-ENAMETOOLONG); } *pbase = base; -- 2.46.1

8 months, 1 week

2
1
0 0

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Linux-stable-mirror January 2025