search for: warn_on_once

Yeah, we shouldn't let the machine die. Are there more WARN_ON_ONCE usage we could convert to WARN_ONCE? Reviewed-By: Karol Herbst <karolherbst at gmail.com> On Fri, Jul 14, 2017 at 5:05 PM, Tobias Klausmann <tobias.johannes.klausmann at mni.thm.de> wrote: > On 7/14/17 3:41 PM, Mike Galbraith wrote: >> >> On Fri, 2017-07-14 at 15:36 +02...

On Fri, 2017-07-14 at 15:36 +0200, Mike Galbraith wrote: >  All DRM did was to slip a > WARN_ON_ONCE() that nouveau triggers into a kernel module where such > things no longer warn, they blow the box out of the water. BTW, turn that irksome WARN_ON_ONCE() in drivers/gpu/drm/drm_vblank.c into a WARN_ONCE(), and all is peachy, you get the warning, box lives. --- drivers/gpu/drm/drm_vblank.c |...

...v4.12 backmerge at > any point. The last backmerge from Linus as far as I can tell was > v4.11-rc7. Could be an interaction with some out-of-tree change. Ok, a network outage gave me time to go hunting.  Indeed it is a bad interaction with the tree DRM merged into.  All DRM did was to slip a WARN_ON_ONCE() that nouveau triggers into a kernel module where such things no longer warn, they blow the box out of the water.  I made a dinky testcase module (attached), and bisected to the real root.... 19d436268dde95389c616bb3819da73f0a8b28a8 is the first bad commit commit 19d436268dde95389c616bb3819da73f0...

...-- a/tools/virtio/linux/kernel.h +++ b/tools/virtio/linux/kernel.h @@ -123,7 +123,7 @@ static inline void free_page(unsigned long addr) #define dev_err(dev, format, ...) fprintf (stderr, format, ## __VA_ARGS__) #define dev_warn(dev, format, ...) fprintf (stderr, format, ## __VA_ARGS__) -#define WARN_ON_ONCE(cond) ((cond) ? fprintf (stderr, "WARNING\n") : 0) +#define WARN_ON_ONCE(cond) (unlikely(cond) ? fprintf (stderr, "WARNING\n") : 0) #define min(x, y) ({ \ typeof(x) _min1 = (x); \ -- 2.17.1

...es.klausmann at mni.thm.de> wrote: > The conversion is a nice catch, but i'd like to have a bit more context, see > below! > > With a better description: > > Tobias Klausmann <tobias.johannes.klausmann at mni.thm.de> I don't think it was meant as a serious patch. WARN_ON_ONCE should work. The fix isn't to remove all instances of WARN_ON_ONCE. The fix is to fix WARN_ON_ONCE.

....c >> +++ b/mm/page_isolation.c >> @@ -58,16 +58,12 @@ static int set_migratetype_isolate(struct page *page, int migratetype, int isol_ >> spin_unlock_irqrestore(&zone->lock, flags); >> if (!ret) { >> drain_all_pages(zone); >> - } else { >> - WARN_ON_ONCE(zone_idx(zone) == ZONE_MOVABLE); >> - >> - if ((isol_flags & REPORT_FAILURE) && unmovable) >> - /* >> - * printk() with zone->lock held will likely trigger a >> - * lockdep splat, so defer it here. >> - */ >> - dump_page(unmovab...

...6 deletions(-) diff --git a/fs/dax.c b/fs/dax.c index 994ab66a9907..8eddbcc0e149 100644 --- a/fs/dax.c +++ b/fs/dax.c @@ -358,7 +358,7 @@ static void dax_disassociate_entry(void *entry, struct address_space *mapping, for_each_mapped_pfn(entry, pfn) { struct page *page = pfn_to_page(pfn); - WARN_ON_ONCE(trunc && page_ref_count(page) > 1); + WARN_ON_ONCE(trunc && !dax_layout_is_idle_page(page)); WARN_ON_ONCE(page->mapping && page->mapping != mapping); page->mapping = NULL; page->index = 0; @@ -372,7 +372,7 @@ static struct page *dax_busy_page(void *e...

.../* * With DEBUG_HIGHMEM the stack depth is doubled and every second * slot is unused which acts as a guard page @@ -379,23 +377,21 @@ static DEFINE_PER_CPU(int, __kmap_local_ static inline int kmap_local_idx_push(void) { - int idx = __this_cpu_add_return(__kmap_local_idx, KM_INCR) - 1; - WARN_ON_ONCE(in_irq() && !irqs_disabled()); - BUG_ON(idx >= KM_MAX_IDX); - return idx; + current->kmap_ctrl.idx += KM_INCR; + BUG_ON(current->kmap_ctrl.idx >= KM_TYPE_NR); + return current->kmap_ctrl.idx - 1; } static inline int kmap_local_idx(void) { - return __this_cpu_read(__kmap_...

The conversion is a nice catch, but i'd like to have a bit more context, see below! With a better description: Tobias Klausmann <tobias.johannes.klausmann at mni.thm.de> On 7/14/17 5:10 PM, Karol Herbst wrote: > Yeah, we shouldn't let the machine die. Are there more WARN_ON_ONCE > usage we could convert to WARN_ONCE? > > Reviewed-By: Karol Herbst <karolherbst at gmail.com> > > On Fri, Jul 14, 2017 at 5:05 PM, Tobias Klausmann > <tobias.johannes.klausmann at mni.thm.de> wrote: >> On 7/14/17 3:41 PM, Mike Galbraith wrote: >>> On F...

...of metadata (memmap, page tables, memory block device, etc.). The only way it could really fail currently is when injecting allocation errors. All other error cases inside release_mem_region_adjustable() seem to be sanity checks if the function would be abused in different context - let's add WARN_ON_ONCE(). Cc: Andrew Morton <akpm at linux-foundation.org> Cc: Michal Hocko <mhocko at suse.com> Cc: Dan Williams <dan.j.williams at intel.com> Cc: Jason Gunthorpe <jgg at ziepe.ca> Cc: Kees Cook <keescook at chromium.org> Cc: Ard Biesheuvel <ardb at kernel.org> Cc: Pa...

...t of metadata (memmap, page tables, memory block device, etc.). The only reason it could really fail would be when injecting allocation errors. All other error cases inside release_mem_region_adjustable() seem to be sanity checks if the function would be abused in different context - let's add WARN_ON_ONCE() in these cases so we can catch them. Cc: Andrew Morton <akpm at linux-foundation.org> Cc: Michal Hocko <mhocko at suse.com> Cc: Dan Williams <dan.j.williams at intel.com> Cc: Jason Gunthorpe <jgg at ziepe.ca> Cc: Kees Cook <keescook at chromium.org> Cc: Ard Biesheuv...

On 7/14/17 3:41 PM, Mike Galbraith wrote: > On Fri, 2017-07-14 at 15:36 +0200, Mike Galbraith wrote: >>  All DRM did was to slip a >> WARN_ON_ONCE() that nouveau triggers into a kernel module where such >> things no longer warn, they blow the box out of the water. > BTW, turn that irksome WARN_ON_ONCE() in drivers/gpu/drm/drm_vblank.c > into a WARN_ONCE(), and all is peachy, you get the warning, box lives. > > --- > dri...

...9 deletions(-) diff --git a/fs/dax.c b/fs/dax.c index 5b47834f2e1b..85c63f735909 100644 --- a/fs/dax.c +++ b/fs/dax.c @@ -358,7 +358,7 @@ static void dax_disassociate_entry(void *entry, struct address_space *mapping, for_each_mapped_pfn(entry, pfn) { struct page *page = pfn_to_page(pfn); - WARN_ON_ONCE(trunc && page_ref_count(page) > 1); + WARN_ON_ONCE(trunc && !dax_layout_is_idle_page(page)); WARN_ON_ONCE(page->mapping && page->mapping != mapping); page->mapping = NULL; page->index = 0; @@ -372,7 +372,7 @@ static struct page *dax_busy_page(void *e...

dma_addressing_limited() should not be called on a device with a NULL dma_mask. If this occurs let's WARN_ON_ONCE and immediately return. Existing call sites are updated separately. Fixes: b866455423e0 ("dma-mapping: add a dma_addressing_limited helper") Signed-off-by: Eric Auger <eric.auger at redhat.com> --- v1 -> v2: - add a WARN_ON_ONCE() - reword the commit message --- include/linux...

...unplugged. > > Cleanup has_unmovable_pages() and set_migratetype_isolate(), providing > better documentation of how ZONE_MOVABLE interacts with different kind of > unmovable pages (memory offlining vs. alloc_contig_range()). > > v3 -> v4: > - "mm/page_isolation: drop WARN_ON_ONCE() in set_migratetype_isolate()" > -- Fix typo in description > - "virtio-mem: don't special-case ZONE_MOVABLE" > -- Add more details why we initialli special-cased ZONE_MOVABLE (via MST) > - "mm: document semantics of ZONE_MOVABLE" > -- Rephrase some part...

We currently have cases where the dma_addressing_limited() gets called with dma_mask unset. This causes a NULL pointer dereference. Use dma_get_mask() accessor to prevent the crash. Fixes: b866455423e0 ("dma-mapping: add a dma_addressing_limited helper") Signed-off-by: Eric Auger <eric.auger at redhat.com> --- v1 -> v2: - was [PATCH 1/2] dma-mapping: Protect

We currently have cases where the dma_addressing_limited() gets called with dma_mask unset. This causes a NULL pointer dereference. Use dma_get_mask() accessor to prevent the crash. Fixes: b866455423e0 ("dma-mapping: add a dma_addressing_limited helper") Signed-off-by: Eric Auger <eric.auger at redhat.com> --- v1 -> v2: - was [PATCH 1/2] dma-mapping: Protect

When running a guest featuring a virtio-blk-pci protected with a virtual IOMMU we hit a NULL pointer dereference. This series removes the dma_max_mapping_size() call in virtio_max_dma_size when the device does not have any dma_mask set. A check is also added to early return in dma_addressing_limited() if the dma_mask is NULL. Eric Auger (2): dma-mapping: Protect dma_addressing_limited against

Switch the function documentation to kerneldoc comments, and add WARN_ON_ONCE asserts that the calling thread is a kernel thread and does not have ->mm set (or has ->mm set in the case of unuse_mm). Also give the functions a kthread_ prefix to better document the use case. Signed-off-by: Christoph Hellwig <hch at lst.de> --- drivers/gpu/drm/amd/amdgpu/amdgpu_a...

...07..8eddbcc0e149 100644 > --- a/fs/dax.c > +++ b/fs/dax.c > @@ -358,7 +358,7 @@ static void dax_disassociate_entry(void *entry, struct address_space *mapping, > for_each_mapped_pfn(entry, pfn) { > struct page *page = pfn_to_page(pfn); > > - WARN_ON_ONCE(trunc && page_ref_count(page) > 1); > + WARN_ON_ONCE(trunc && !dax_layout_is_idle_page(page)); > WARN_ON_ONCE(page->mapping && page->mapping != mapping); > page->mapping = NULL; > page->...