search for: config_debug_vm

On Thu 19-04-18 12:12:38, Mikulas Patocka wrote: [...] > From: Mikulas Patocka <mpatocka at redhat.com> > Subject: [PATCH] kvmalloc: always use vmalloc if CONFIG_DEBUG_VM > > The kvmalloc function tries to use kmalloc and falls back to vmalloc if > kmalloc fails. > > Unfortunatelly, some kernel code has bugs - it uses kvmalloc and then > uses DMA-API on the returned memory or frees it with kfree. Such bugs were > found in the virtio-net driver...

On Thu 19-04-18 12:12:38, Mikulas Patocka wrote: [...] > From: Mikulas Patocka <mpatocka at redhat.com> > Subject: [PATCH] kvmalloc: always use vmalloc if CONFIG_DEBUG_VM > > The kvmalloc function tries to use kmalloc and falls back to vmalloc if > kmalloc fails. > > Unfortunatelly, some kernel code has bugs - it uses kvmalloc and then > uses DMA-API on the returned memory or frees it with kfree. Such bugs were > found in the virtio-net driver...

On Fri 20-04-18 06:41:36, Matthew Wilcox wrote: > On Fri, Apr 20, 2018 at 03:08:52PM +0200, Michal Hocko wrote: > > > In order to detect these bugs reliably I submit this patch that changes > > > kvmalloc to always use vmalloc if CONFIG_DEBUG_VM is turned on. > > > > No way. This is just wrong! First of all, you will explode most likely > > on many allocations of small sizes. Second, CONFIG_DEBUG_VM tends to be > > enabled quite often. > > I think it'll still suit Mikulas' debugging needs if we alway...

On Fri, Apr 20, 2018 at 04:54:53PM -0400, Mikulas Patocka wrote: > On Fri, 20 Apr 2018, Michal Hocko wrote: > > No way. This is just wrong! First of all, you will explode most likely > > on many allocations of small sizes. Second, CONFIG_DEBUG_VM tends to be > > enabled quite often. > > You're an evil person who doesn't want to fix bugs. Steady on. There's no need for that. Michal isn't evil. Please apologise. > You refused to fix vmalloc(GFP_NOIO) misbehavior a year ago (did you make > some progress...

On Fri, Apr 20, 2018 at 04:54:53PM -0400, Mikulas Patocka wrote: > On Fri, 20 Apr 2018, Michal Hocko wrote: > > No way. This is just wrong! First of all, you will explode most likely > > on many allocations of small sizes. Second, CONFIG_DEBUG_VM tends to be > > enabled quite often. > > You're an evil person who doesn't want to fix bugs. Steady on. There's no need for that. Michal isn't evil. Please apologise. > You refused to fix vmalloc(GFP_NOIO) misbehavior a year ago (did you make > some progress...

...rity or RHEL7 powerpc-specific > code. > > These bugs are hard to reproduce because vmalloc falls back to kmalloc > only if memory is fragmented. Yes, that's nasty. > In order to detect these bugs reliably I submit this patch that changes > kvmalloc to always use vmalloc if CONFIG_DEBUG_VM is turned on. > > ... > > --- linux-2.6.orig/mm/util.c 2018-04-18 15:46:23.000000000 +0200 > +++ linux-2.6/mm/util.c 2018-04-18 16:00:43.000000000 +0200 > @@ -395,6 +395,7 @@ EXPORT_SYMBOL(vm_mmap); > */ > void *kvmalloc_node(size_t size, gfp_t flags, int node) > { &...

...rity or RHEL7 powerpc-specific > code. > > These bugs are hard to reproduce because vmalloc falls back to kmalloc > only if memory is fragmented. Yes, that's nasty. > In order to detect these bugs reliably I submit this patch that changes > kvmalloc to always use vmalloc if CONFIG_DEBUG_VM is turned on. > > ... > > --- linux-2.6.orig/mm/util.c 2018-04-18 15:46:23.000000000 +0200 > +++ linux-2.6/mm/util.c 2018-04-18 16:00:43.000000000 +0200 > @@ -395,6 +395,7 @@ EXPORT_SYMBOL(vm_mmap); > */ > void *kvmalloc_node(size_t size, gfp_t flags, int node) > { &...

...usually returns DMA-able area, but it > may return non-DMA area rarely, if the memory is too fragmented. So, we > are in a situation, where some networking drivers will randomly fail. Go > and find them. > > Mikulas Her I submit a patch that makes kvmalloc always use vmalloc if CONFIG_DEBUG_VM is defined. From: Mikulas Patocka <mpatocka at redhat.com> Subject: [PATCH] kvmalloc: always use vmalloc if CONFIG_DEBUG_VM The kvmalloc function tries to use kmalloc and falls back to vmalloc if kmalloc fails. Unfortunatelly, some kernel code has bugs - it uses kvmalloc and then uses D...

...Apr 2018, Matthew Wilcox wrote: > On Fri, Apr 20, 2018 at 04:54:53PM -0400, Mikulas Patocka wrote: > > On Fri, 20 Apr 2018, Michal Hocko wrote: > > > No way. This is just wrong! First of all, you will explode most likely > > > on many allocations of small sizes. Second, CONFIG_DEBUG_VM tends to be > > > enabled quite often. > > > > You're an evil person who doesn't want to fix bugs. > > Steady on. There's no need for that. Michal isn't evil. Please > apologise. I see this attitude from Michal again and again. He didn't want...

On Wed, 18 Apr 2018, David Miller wrote: > From: Mikulas Patocka <mpatocka at redhat.com> > Date: Wed, 18 Apr 2018 12:44:25 -0400 (EDT) > > > The structure net_device is followed by arbitrary driver-specific data > > (accessible with the function netdev_priv). And for virtio-net, these > > driver-specific data must be in DMA memory. > > And we are saying

...gt; > may return non-DMA area rarely, if the memory is too fragmented. So, we > > are in a situation, where some networking drivers will randomly fail. Go > > and find them. > > > > Mikulas > > Her I submit a patch that makes kvmalloc always use vmalloc if > CONFIG_DEBUG_VM is defined. > > > > > From: Mikulas Patocka <mpatocka at redhat.com> > Subject: [PATCH] kvmalloc: always use vmalloc if CONFIG_DEBUG_VM > > The kvmalloc function tries to use kmalloc and falls back to vmalloc if > kmalloc fails. > > Unfortunatelly, some...

.... > > > > These bugs are hard to reproduce because vmalloc falls back to kmalloc > > only if memory is fragmented. > > Yes, that's nasty. > > > In order to detect these bugs reliably I submit this patch that changes > > kvmalloc to always use vmalloc if CONFIG_DEBUG_VM is turned on. > > > > ... > > > > --- linux-2.6.orig/mm/util.c 2018-04-18 15:46:23.000000000 +0200 > > +++ linux-2.6/mm/util.c 2018-04-18 16:00:43.000000000 +0200 > > @@ -395,6 +395,7 @@ EXPORT_SYMBOL(vm_mmap); > > */ > > void *kvmalloc_node(size_...

On Fri, 20 Apr 2018, Michal Hocko wrote: > On Thu 19-04-18 12:12:38, Mikulas Patocka wrote: > [...] > > From: Mikulas Patocka <mpatocka at redhat.com> > > Subject: [PATCH] kvmalloc: always use vmalloc if CONFIG_DEBUG_VM > > > > The kvmalloc function tries to use kmalloc and falls back to vmalloc if > > kmalloc fails. > > > > Unfortunatelly, some kernel code has bugs - it uses kvmalloc and then > > uses DMA-API on the returned memory or frees it with kfree. Such bugs were >...

On Thu, 19 Apr 2018 17:19:20 -0400 (EDT) Mikulas Patocka <mpatocka at redhat.com> wrote: > > > In order to detect these bugs reliably I submit this patch that changes > > > kvmalloc to always use vmalloc if CONFIG_DEBUG_VM is turned on. > > > > > > ... > > > > > > --- linux-2.6.orig/mm/util.c 2018-04-18 15:46:23.000000000 +0200 > > > +++ linux-2.6/mm/util.c 2018-04-18 16:00:43.000000000 +0200 > > > @@ -395,6 +395,7 @@ EXPORT_SYMBOL(vm_mmap); > > > */ &...

On Fri, Apr 20, 2018 at 03:08:52PM +0200, Michal Hocko wrote: > > In order to detect these bugs reliably I submit this patch that changes > > kvmalloc to always use vmalloc if CONFIG_DEBUG_VM is turned on. > > No way. This is just wrong! First of all, you will explode most likely > on many allocations of small sizes. Second, CONFIG_DEBUG_VM tends to be > enabled quite often. I think it'll still suit Mikulas' debugging needs if we always use vmalloc for sizes above...

...gt; > On Fri, Apr 20, 2018 at 04:54:53PM -0400, Mikulas Patocka wrote: > > > > On Fri, 20 Apr 2018, Michal Hocko wrote: > > > > > No way. This is just wrong! First of all, you will explode most likely > > > > > on many allocations of small sizes. Second, CONFIG_DEBUG_VM tends to be > > > > > enabled quite often. > > > > > > > > You're an evil person who doesn't want to fix bugs. > > > > > > Steady on. There's no need for that. Michal isn't evil. Please > > > apologise. > >...

...gt; > On Fri, Apr 20, 2018 at 04:54:53PM -0400, Mikulas Patocka wrote: > > > > On Fri, 20 Apr 2018, Michal Hocko wrote: > > > > > No way. This is just wrong! First of all, you will explode most likely > > > > > on many allocations of small sizes. Second, CONFIG_DEBUG_VM tends to be > > > > > enabled quite often. > > > > > > > > You're an evil person who doesn't want to fix bugs. > > > > > > Steady on. There's no need for that. Michal isn't evil. Please > > > apologise. > >...

On Mon 23-04-18 10:24:02, Mikulas Patocka wrote: [...] I am not going to comment on your continuous accusations. We can discuss patches but general rants make very limited sense. > > > > I already said that we can change it from CONFIG_DEBUG_VM to > > > > CONFIG_DEBUG_SG - or to whatever other option you may want, just to make > > > > sure that it is enabled in distro debug kernels by default. > > > > > > Yes, and I think that's the right idea. So send a v2 and ignore the > > > re...

...Wilcox wrote: > > On Fri, Apr 20, 2018 at 04:54:53PM -0400, Mikulas Patocka wrote: > > > On Fri, 20 Apr 2018, Michal Hocko wrote: > > > > No way. This is just wrong! First of all, you will explode most likely > > > > on many allocations of small sizes. Second, CONFIG_DEBUG_VM tends to be > > > > enabled quite often. > > > > > > You're an evil person who doesn't want to fix bugs. > > > > Steady on. There's no need for that. Michal isn't evil. Please > > apologise. > > I see this attitude from Mic...

...Wilcox wrote: > > On Fri, Apr 20, 2018 at 04:54:53PM -0400, Mikulas Patocka wrote: > > > On Fri, 20 Apr 2018, Michal Hocko wrote: > > > > No way. This is just wrong! First of all, you will explode most likely > > > > on many allocations of small sizes. Second, CONFIG_DEBUG_VM tends to be > > > > enabled quite often. > > > > > > You're an evil person who doesn't want to fix bugs. > > > > Steady on. There's no need for that. Michal isn't evil. Please > > apologise. > > I see this attitude from Mic...