From: Dan Williams <dan.j.williams@intel.com> To: linux-nvdimm@lists.01.org Cc: Andrew Morton <akpm@linux-foundation.org>, Jeff Moyer <jmoyer@redhat.com>, linux-kernel@vger.kernel.org Subject: [PATCH 3/3] devm_memremap_pages: fix vmem_altmap lifetime + alignment handling Date: Sat, 30 Jan 2016 10:42:19 -0800 [thread overview] Message-ID: <20160130184219.17558.88859.stgit@dwillia2-desk3.amr.corp.intel.com> (raw) In-Reply-To: <20160130184203.17558.30413.stgit@dwillia2-desk3.amr.corp.intel.com> to_vmem_altmap() needs to return valid results until arch_remove_memory() completes. It also needs to be valid for any pfn in a section regardless of whether that pfn maps to data. This escape was a result of a bug in the unit test. The signature of this bug is that free_pagetable() fails to retrieve a vmem_altmap and goes off into the weeds: BUG: unable to handle kernel NULL pointer dereference at (null) IP: [<ffffffff811d2629>] get_pfnblock_flags_mask+0x49/0x60 [..] Call Trace: [<ffffffff811d3477>] free_hot_cold_page+0x97/0x1d0 [<ffffffff811d367a>] __free_pages+0x2a/0x40 [<ffffffff8191e669>] free_pagetable+0x8c/0xd4 [<ffffffff8191ef4e>] remove_pagetable+0x37a/0x808 [<ffffffff8191b210>] vmemmap_free+0x10/0x20 Fixes: 4b94ffdc4163 ("x86, mm: introduce vmem_altmap to augment vmemmap_populate()") Cc: Andrew Morton <akpm@linux-foundation.org> Reported-by: Jeff Moyer <jmoyer@redhat.com> Signed-off-by: Dan Williams <dan.j.williams@intel.com> --- kernel/memremap.c | 18 +++++++++++------- 1 file changed, 11 insertions(+), 7 deletions(-) diff --git a/kernel/memremap.c b/kernel/memremap.c index e517a16cb426..cbc3e97e2bb4 100644 --- a/kernel/memremap.c +++ b/kernel/memremap.c @@ -183,7 +183,11 @@ EXPORT_SYMBOL(put_zone_device_page); static void pgmap_radix_release(struct resource *res) { - resource_size_t key; + resource_size_t key, align_start, align_size, align_end; + + align_start = res->start & ~(SECTION_SIZE - 1); + align_size = ALIGN(resource_size(res), SECTION_SIZE); + align_end = align_start + align_size - 1; mutex_lock(&pgmap_lock); for (key = res->start; key <= res->end; key += SECTION_SIZE) @@ -226,12 +230,11 @@ static void devm_memremap_pages_release(struct device *dev, void *data) percpu_ref_put(pgmap->ref); } - pgmap_radix_release(res); - /* pages are dead and unused, undo the arch mapping */ align_start = res->start & ~(SECTION_SIZE - 1); align_size = ALIGN(resource_size(res), SECTION_SIZE); arch_remove_memory(align_start, align_size); + pgmap_radix_release(res); dev_WARN_ONCE(dev, pgmap->altmap && pgmap->altmap->alloc, "%s: failed to free all reserved pages\n", __func__); } @@ -267,7 +270,7 @@ void *devm_memremap_pages(struct device *dev, struct resource *res, { int is_ram = region_intersects(res->start, resource_size(res), "System RAM"); - resource_size_t key, align_start, align_size; + resource_size_t key, align_start, align_size, align_end; struct dev_pagemap *pgmap; struct page_map *page_map; unsigned long pfn; @@ -309,7 +312,10 @@ void *devm_memremap_pages(struct device *dev, struct resource *res, mutex_lock(&pgmap_lock); error = 0; - for (key = res->start; key <= res->end; key += SECTION_SIZE) { + align_start = res->start & ~(SECTION_SIZE - 1); + align_size = ALIGN(resource_size(res), SECTION_SIZE); + align_end = align_start + align_size - 1; + for (key = align_start; key <= align_end; key += SECTION_SIZE) { struct dev_pagemap *dup; rcu_read_lock(); @@ -336,8 +342,6 @@ void *devm_memremap_pages(struct device *dev, struct resource *res, if (nid < 0) nid = numa_mem_id(); - align_start = res->start & ~(SECTION_SIZE - 1); - align_size = ALIGN(resource_size(res), SECTION_SIZE); error = arch_add_memory(nid, align_start, align_size, true); if (error) goto err_add_memory;
WARNING: multiple messages have this Message-ID (diff)
From: Dan Williams <dan.j.williams@intel.com> To: linux-nvdimm@ml01.01.org Cc: Andrew Morton <akpm@linux-foundation.org>, Jeff Moyer <jmoyer@redhat.com>, linux-kernel@vger.kernel.org Subject: [PATCH 3/3] devm_memremap_pages: fix vmem_altmap lifetime + alignment handling Date: Sat, 30 Jan 2016 10:42:19 -0800 [thread overview] Message-ID: <20160130184219.17558.88859.stgit@dwillia2-desk3.amr.corp.intel.com> (raw) In-Reply-To: <20160130184203.17558.30413.stgit@dwillia2-desk3.amr.corp.intel.com> to_vmem_altmap() needs to return valid results until arch_remove_memory() completes. It also needs to be valid for any pfn in a section regardless of whether that pfn maps to data. This escape was a result of a bug in the unit test. The signature of this bug is that free_pagetable() fails to retrieve a vmem_altmap and goes off into the weeds: BUG: unable to handle kernel NULL pointer dereference at (null) IP: [<ffffffff811d2629>] get_pfnblock_flags_mask+0x49/0x60 [..] Call Trace: [<ffffffff811d3477>] free_hot_cold_page+0x97/0x1d0 [<ffffffff811d367a>] __free_pages+0x2a/0x40 [<ffffffff8191e669>] free_pagetable+0x8c/0xd4 [<ffffffff8191ef4e>] remove_pagetable+0x37a/0x808 [<ffffffff8191b210>] vmemmap_free+0x10/0x20 Fixes: 4b94ffdc4163 ("x86, mm: introduce vmem_altmap to augment vmemmap_populate()") Cc: Andrew Morton <akpm@linux-foundation.org> Reported-by: Jeff Moyer <jmoyer@redhat.com> Signed-off-by: Dan Williams <dan.j.williams@intel.com> --- kernel/memremap.c | 18 +++++++++++------- 1 file changed, 11 insertions(+), 7 deletions(-) diff --git a/kernel/memremap.c b/kernel/memremap.c index e517a16cb426..cbc3e97e2bb4 100644 --- a/kernel/memremap.c +++ b/kernel/memremap.c @@ -183,7 +183,11 @@ EXPORT_SYMBOL(put_zone_device_page); static void pgmap_radix_release(struct resource *res) { - resource_size_t key; + resource_size_t key, align_start, align_size, align_end; + + align_start = res->start & ~(SECTION_SIZE - 1); + align_size = ALIGN(resource_size(res), SECTION_SIZE); + align_end = align_start + align_size - 1; mutex_lock(&pgmap_lock); for (key = res->start; key <= res->end; key += SECTION_SIZE) @@ -226,12 +230,11 @@ static void devm_memremap_pages_release(struct device *dev, void *data) percpu_ref_put(pgmap->ref); } - pgmap_radix_release(res); - /* pages are dead and unused, undo the arch mapping */ align_start = res->start & ~(SECTION_SIZE - 1); align_size = ALIGN(resource_size(res), SECTION_SIZE); arch_remove_memory(align_start, align_size); + pgmap_radix_release(res); dev_WARN_ONCE(dev, pgmap->altmap && pgmap->altmap->alloc, "%s: failed to free all reserved pages\n", __func__); } @@ -267,7 +270,7 @@ void *devm_memremap_pages(struct device *dev, struct resource *res, { int is_ram = region_intersects(res->start, resource_size(res), "System RAM"); - resource_size_t key, align_start, align_size; + resource_size_t key, align_start, align_size, align_end; struct dev_pagemap *pgmap; struct page_map *page_map; unsigned long pfn; @@ -309,7 +312,10 @@ void *devm_memremap_pages(struct device *dev, struct resource *res, mutex_lock(&pgmap_lock); error = 0; - for (key = res->start; key <= res->end; key += SECTION_SIZE) { + align_start = res->start & ~(SECTION_SIZE - 1); + align_size = ALIGN(resource_size(res), SECTION_SIZE); + align_end = align_start + align_size - 1; + for (key = align_start; key <= align_end; key += SECTION_SIZE) { struct dev_pagemap *dup; rcu_read_lock(); @@ -336,8 +342,6 @@ void *devm_memremap_pages(struct device *dev, struct resource *res, if (nid < 0) nid = numa_mem_id(); - align_start = res->start & ~(SECTION_SIZE - 1); - align_size = ALIGN(resource_size(res), SECTION_SIZE); error = arch_add_memory(nid, align_start, align_size, true); if (error) goto err_add_memory;
next prev parent reply other threads:[~2016-01-30 18:42 UTC|newest] Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top 2016-01-30 18:42 [PATCH 0/3] libnvdimm: fix memmap in pmem support Dan Williams 2016-01-30 18:42 ` Dan Williams 2016-01-30 18:42 ` [PATCH 1/3] libnvdimm: fix mode determination for e820 devices Dan Williams 2016-01-30 18:42 ` Dan Williams 2016-01-30 18:42 ` [PATCH 2/3] libnvdimm, pfn: fix restoring memmap location Dan Williams 2016-01-30 18:42 ` Dan Williams 2016-01-30 18:42 ` Dan Williams [this message] 2016-01-30 18:42 ` [PATCH 3/3] devm_memremap_pages: fix vmem_altmap lifetime + alignment handling Dan Williams
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