| Message ID | 20211122153233.9924-1-mhocko@kernel.org (mailing list archive) |
|---|---|
| Headers | show |
| Series | extend vmalloc support for constrained allocations | expand |
On Mon, Nov 22, 2021 at 04:32:29PM +0100, Michal Hocko wrote: > Hi, > The previous version has been posted here [1] > > I hope I have addressed all the feedback. There were some suggestions > for further improvements but I would rather make this smaller as I > cannot really invest more time and I believe further changes can be done > on top. > > This version is a rebase on top of the current Linus tree. Except for > the review feedback and conflicting changes in the area there is only > one change to filter out __GFP_NOFAIL from the bulk allocator. This is > not necessary strictly speaking AFAICS but I found it less confusing > because vmalloc has its fallback strategy and the bulk allocator is > meant only for the fast path. > > Original cover: > Based on a recent discussion with Dave and Neil [2] I have tried to > implement NOFS, NOIO, NOFAIL support for the vmalloc to make > life of kvmalloc users easier. > > A requirement for NOFAIL support for kvmalloc was new to me but this > seems to be really needed by the xfs code. > > NOFS/NOIO was a known and a long term problem which was hoped to be > handled by the scope API. Those scope should have been used at the > reclaim recursion boundaries both to document them and also to remove > the necessity of NOFS/NOIO constrains for all allocations within that > scope. Instead workarounds were developed to wrap a single allocation > instead (like ceph_kvmalloc). > > First patch implements NOFS/NOIO support for vmalloc. The second one > adds NOFAIL support and the third one bundles all together into kvmalloc > and drops ceph_kvmalloc which can use kvmalloc directly now. > > I hope I haven't missed anything in the vmalloc allocator. Correct __GFP_NOLOCKDEP support is also needed. See: https://lore.kernel.org/linux-mm/20211119225435.GZ449541@dread.disaster.area/ Cheers, Dave.
On Thu 25-11-21 09:55:26, Dave Chinner wrote: [...] > Correct __GFP_NOLOCKDEP support is also needed. See: > > https://lore.kernel.org/linux-mm/20211119225435.GZ449541@dread.disaster.area/ I will have a closer look. This will require changes on both vmalloc and sl?b sides.
[Cc Sebastian and Vlastimil] On Thu 25-11-21 09:58:31, Michal Hocko wrote: > On Thu 25-11-21 09:55:26, Dave Chinner wrote: > [...] > > Correct __GFP_NOLOCKDEP support is also needed. See: > > > > https://lore.kernel.org/linux-mm/20211119225435.GZ449541@dread.disaster.area/ > > I will have a closer look. This will require changes on both vmalloc and > sl?b sides. This should hopefully make the trick --- From 0082d29c771d831e5d1b9bb4c0a61d39bac017f0 Mon Sep 17 00:00:00 2001 From: Michal Hocko <mhocko@suse.com> Date: Thu, 25 Nov 2021 10:20:16 +0100 Subject: [PATCH] mm: make slab and vmalloc allocators __GFP_NOLOCKDEP aware sl?b and vmalloc allocators reduce the given gfp mask for their internal needs. For that they use GFP_RECLAIM_MASK to preserve the reclaim behavior and constrains. __GFP_NOLOCKDEP is not a part of that mask because it doesn't really control the reclaim behavior strictly speaking. On the other hand it tells the underlying page allocator to disable reclaim recursion detection so arguably it should be part of the mask. Having __GFP_NOLOCKDEP in the mask will not alter the behavior in any form so this change is safe pretty much by definition. It also adds a support for this flag to SL?B and vmalloc allocators which will in turn allow its use to kvmalloc as well. A lack of the support has been noticed recently in http://lkml.kernel.org/r/20211119225435.GZ449541@dread.disaster.area Reported-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Signed-off-by: Michal Hocko <mhocko@suse.com> --- mm/internal.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/mm/internal.h b/mm/internal.h index 3b79a5c9427a..2ceea20b5b2a 100644 --- a/mm/internal.h +++ b/mm/internal.h @@ -21,7 +21,7 @@ #define GFP_RECLAIM_MASK (__GFP_RECLAIM|__GFP_HIGH|__GFP_IO|__GFP_FS|\ __GFP_NOWARN|__GFP_RETRY_MAYFAIL|__GFP_NOFAIL|\ __GFP_NORETRY|__GFP_MEMALLOC|__GFP_NOMEMALLOC|\ - __GFP_ATOMIC) + __GFP_ATOMIC|__GFP_NOLOCKDEP) /* The GFP flags allowed during early boot */ #define GFP_BOOT_MASK (__GFP_BITS_MASK & ~(__GFP_RECLAIM|__GFP_IO|__GFP_FS))
On Thu, Nov 25, 2021 at 10:30:28AM +0100, Michal Hocko wrote: > [Cc Sebastian and Vlastimil] > > On Thu 25-11-21 09:58:31, Michal Hocko wrote: > > On Thu 25-11-21 09:55:26, Dave Chinner wrote: > > [...] > > > Correct __GFP_NOLOCKDEP support is also needed. See: > > > > > > https://lore.kernel.org/linux-mm/20211119225435.GZ449541@dread.disaster.area/ > > > > I will have a closer look. This will require changes on both vmalloc and > > sl?b sides. > > This should hopefully make the trick > --- > From 0082d29c771d831e5d1b9bb4c0a61d39bac017f0 Mon Sep 17 00:00:00 2001 > From: Michal Hocko <mhocko@suse.com> > Date: Thu, 25 Nov 2021 10:20:16 +0100 > Subject: [PATCH] mm: make slab and vmalloc allocators __GFP_NOLOCKDEP aware > > sl?b and vmalloc allocators reduce the given gfp mask for their internal > needs. For that they use GFP_RECLAIM_MASK to preserve the reclaim > behavior and constrains. > > __GFP_NOLOCKDEP is not a part of that mask because it doesn't really > control the reclaim behavior strictly speaking. On the other hand > it tells the underlying page allocator to disable reclaim recursion > detection so arguably it should be part of the mask. > > Having __GFP_NOLOCKDEP in the mask will not alter the behavior in any > form so this change is safe pretty much by definition. It also adds > a support for this flag to SL?B and vmalloc allocators which will in > turn allow its use to kvmalloc as well. A lack of the support has been > noticed recently in http://lkml.kernel.org/r/20211119225435.GZ449541@dread.disaster.area > > Reported-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> > Signed-off-by: Michal Hocko <mhocko@suse.com> > --- > mm/internal.h | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/mm/internal.h b/mm/internal.h > index 3b79a5c9427a..2ceea20b5b2a 100644 > --- a/mm/internal.h > +++ b/mm/internal.h > @@ -21,7 +21,7 @@ > #define GFP_RECLAIM_MASK (__GFP_RECLAIM|__GFP_HIGH|__GFP_IO|__GFP_FS|\ > __GFP_NOWARN|__GFP_RETRY_MAYFAIL|__GFP_NOFAIL|\ > __GFP_NORETRY|__GFP_MEMALLOC|__GFP_NOMEMALLOC|\ > - __GFP_ATOMIC) > + __GFP_ATOMIC|__GFP_NOLOCKDEP) > > /* The GFP flags allowed during early boot */ > #define GFP_BOOT_MASK (__GFP_BITS_MASK & ~(__GFP_RECLAIM|__GFP_IO|__GFP_FS)) Looks reasonable to me. Acked-by: Dave Chinner <dchinner@redhat.com> Cheers, Dave.
On 11/25/21 10:30, Michal Hocko wrote: > [Cc Sebastian and Vlastimil] > > On Thu 25-11-21 09:58:31, Michal Hocko wrote: >> On Thu 25-11-21 09:55:26, Dave Chinner wrote: >> [...] >> > Correct __GFP_NOLOCKDEP support is also needed. See: >> > >> > https://lore.kernel.org/linux-mm/20211119225435.GZ449541@dread.disaster.area/ >> >> I will have a closer look. This will require changes on both vmalloc and >> sl?b sides. > > This should hopefully make the trick > --- > From 0082d29c771d831e5d1b9bb4c0a61d39bac017f0 Mon Sep 17 00:00:00 2001 > From: Michal Hocko <mhocko@suse.com> > Date: Thu, 25 Nov 2021 10:20:16 +0100 > Subject: [PATCH] mm: make slab and vmalloc allocators __GFP_NOLOCKDEP aware > > sl?b and vmalloc allocators reduce the given gfp mask for their internal > needs. For that they use GFP_RECLAIM_MASK to preserve the reclaim > behavior and constrains. > > __GFP_NOLOCKDEP is not a part of that mask because it doesn't really > control the reclaim behavior strictly speaking. On the other hand > it tells the underlying page allocator to disable reclaim recursion > detection so arguably it should be part of the mask. > > Having __GFP_NOLOCKDEP in the mask will not alter the behavior in any > form so this change is safe pretty much by definition. It also adds > a support for this flag to SL?B and vmalloc allocators which will in > turn allow its use to kvmalloc as well. A lack of the support has been > noticed recently in http://lkml.kernel.org/r/20211119225435.GZ449541@dread.disaster.area > > Reported-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> > Signed-off-by: Michal Hocko <mhocko@suse.com> Acked-by: Vlastimil Babka <vbabka@suse.cz> > --- > mm/internal.h | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/mm/internal.h b/mm/internal.h > index 3b79a5c9427a..2ceea20b5b2a 100644 > --- a/mm/internal.h > +++ b/mm/internal.h > @@ -21,7 +21,7 @@ > #define GFP_RECLAIM_MASK (__GFP_RECLAIM|__GFP_HIGH|__GFP_IO|__GFP_FS|\ > __GFP_NOWARN|__GFP_RETRY_MAYFAIL|__GFP_NOFAIL|\ > __GFP_NORETRY|__GFP_MEMALLOC|__GFP_NOMEMALLOC|\ > - __GFP_ATOMIC) > + __GFP_ATOMIC|__GFP_NOLOCKDEP) > > /* The GFP flags allowed during early boot */ > #define GFP_BOOT_MASK (__GFP_BITS_MASK & ~(__GFP_RECLAIM|__GFP_IO|__GFP_FS)) >